Tuesday, September 24, 2013

CGMINER ASIC FPGA GPU

This is the official thread for support and development of cgminer, the combined GPU and FPGA bitcoin and litecoin miner written in c, cross platform for windows and linux, with overclocking, monitoring, fanspeed control and remote interface capabilities, completely overhauled based on the original code cpuminer.


This code is provided entirely free of charge by the programmer in his spare

time so donations would be greatly appreciated.


Help can also be obtained on IRC: irc.freenode.net #cgminer

READ THE README INCLUDED IN THE ARCHIVE BEFORE ASKING QUESTIONS WHICH CAN ALSO BE FOUND HERE:
http://ck.kolivas.org/apps/cgminer/README


Note that I can NOT provide personalised support via email or personal messages under normal circumstances so they will usually be ignored.

Apologies, but the demand is just far too great and I must prioritise my time.


All files available from here:
http://ck.kolivas.org/apps/cgminer


As a backup they can be downloaded here:
https://github.com/kanoi/cgminer-binaries


Debug builds are in http://ck.kolivas.org/apps/cgminer/debug/


.lrz files are compressed with lrzip http://lrzip.kolivas.org for much better compression and supports extreme encryption technology which is ideal for securing wallets.


LATEST RELEASE: 3.4.3
https://bitcointalk.org/index.php?topic=28402.msg3144100#msg3144100


Note that x86_64 binary is a 64 bit binary for UBUNTU 13.04.


Git tree:
https://github.com/ckolivas/cgminer


Latest git source tarball:
https://github.com/ckolivas/cgminer/tarball/master


Unofficial OSX binaries:
http://spaceman.ca/cgminer/


Features:

- Very low overhead free c code for Linux and windows with very low non-mining CPU and ram usage

- Stratum and GBT pooled mining protocol support

- Scaleable networking scheduler designed to scale to any size hashrate without networking delays yet minimise connection overhead

- Custom modified phatk, poclbm, diablo and diakgcn kernels

- BFI_INT patching

- VECTOR support

- Binary loading of kernels (fast startup)

- long poll support – will use longpoll from any pool if primary pool does not support it

- Self detection of new blocks with a mini-database for slow/failing longpoll scenarios, maximum work efficiency and minimum rejects.

- Heavily threaded code hands out work retrieval and work submission to separate threads to not hinder GPUs working

- Caching of submissions during transient network outages

- Preemptive fetching of work prior to completion of current work

- Local generation of more valid work (ntime rollover) whenever possible, as supported on a per-work item basis

- Prevention of stale work submission on new block

- Multi GPU support (all or discrete selection)

- Summarised and discrete device data statistics of requests, accepts, rejects, hw errors, efficiency and utility

- Watchdog thread to restart idle threads but not crash machine if they don’t respond

- Dynamic intensity that keeps desktop interactive under load and maximises throughput when deskop idle

- Summary displayed when quitting

- Supports multiple pools with multiple intelligent failover mechanisms

- Temporary disabling of misbehaving pools rejecting all shares

- On the fly menu based management of most settings

- Trickling of extra work to backup pools if primary pool is responding but slow

- On the fly enabling/disable/restarting of GPUs

- INTEGRATED GPU MONITORING, OVERCLOCKING AND FANCONTROL

- Auto fan and GPU clocking

- Dual GPU card support

- RPC +/- JSON interface for remote control

- Bitforce support – singles and minirig

- Icarus support

- Ztex support

- Modminer support

- Ability to cope with slow routers

- GPU device reordering by PCI Bus ID

- Submit-old support

- X-Reject-Reason support

- GCN (79×0) support

- Scrypt mining (litecoin)

- Variable difficulty support

- Restarts in the event of crashes

- Share difficulty reporting

- Target and block difficulty displays

- Block solve detection

- ASIC Avalon support

- Bitburner support

- Direct USB communications

- Device hotplug

- Heavily featured RPC API

- Multicast support

- Proxy support

- Lots of other stuff I can’t remember. See options.


Sample output:


Code:

cgminer version 3.3.4 – Started: [2013-08-21 20:51:35]

——————————————————————————–

(5s):133.2G (avg):133.7Gh/s | A:163264  R:460  HW:3069  WU:1871.0/m

ST: 2  SS: 5  NB: 11  LW: 165335  GF: 1  RF: 1

Connected to au.ozco.in diff 92 with stratum as user ckolivas.0

Block: 0015d36cd92d21d4…  Diff:50.8M  Started: [22:12:07]  Best share: 4.92M

——————————————————————————–

[P]ool management [S]ettings [D]isplay options [Q]uit

BAJ 0:  max 48C 3.45V | 8.407G/8.442Gh/s | A: 8849 R:184 HW: 152 WU: 118.3/m

BAS 0:  max 80C 3.28V | 62.85G/62.75Gh/s | A:81501 R:184 HW:1592 WU: 880.6/m

BAS 1:  max 72C 3.27V | 62.72G/62.62Gh/s | A:72914 R: 92 HW:1329 WU: 873.9/m

——————————————————————————–

[2013-08-21 22:15:29] Accepted 000dceb7 Diff 4.75K/92 BAS 0 pool 0

[2013-08-21 22:15:34] Accepted 01731d3c Diff 176/92 BAJ 0 pool 0

[2013-08-21 22:15:34] Accepted 00ab381c Diff 382/92 BAS 0 pool 0

[2013-08-21 22:15:36] Accepted 02af542e Diff 95/92 BAJ 0 pool 0




Pool menu:


Code:

0: Enabled Alive Priority 0: http://www.guugll.eu:11327  User: FTCaddress

1: Enabled Alive Priority  1: http://p2pool.org:9377  User: FTCaddress

2: Disabled Alive Priority 2: http://p2pool.ru:9377  User: FTCaddress

Current pool management strategy: Failover

[F]ailover only disabled

[A]dd pool [R]emove pool [D]isable pool [E]nable pool

[C]hange management strategy [S]witch pool [I]nformation


GPU menu:


Code:

GPU 0: 426.7 / 427.9 Mh/s | A:199  R:0  HW:0  U:6.09/m

72.5 C  F: 50% 4490 RPM)  E: 950 MHz  M: 825 Mhz  V: 1.175V  A: 99% P: 20%

Last initialised: [2011-09-09 12:11:33]

Thread 0: 227.4 Mh/s Enabled ALIVE

Thread 4: 226.1 Mh/s Enabled ALIVE

GPU 1: 426.2 / 427.9 Mh/s | A:186  R:1  HW:0  U:5.69/m

72.5 C  F: 67% 4011 RPM)  E: 950 MHz  M: 825 Mhz  V: 1.175V  A: 99% P: 20%

Last initialised: [2011-09-09 12:11:33]

Thread 1: 213.6 Mh/s Enabled ALIVE

Thread 5: 214.2 Mh/s Enabled ALIVE


GPU 2: 430.9 / 428.0 Mh/s | A:178  R:5  HW:0  U:5.44/m

73.5 C  F: 47% 4247 RPM)  E: 950 MHz  M: 825 Mhz  V: 1.175V  A: 99% P: 20%

Last initialised: [2011-09-09 12:11:33]

Thread 2: 212.8 Mh/s Enabled ALIVE

Thread 6: 188.3 Mh/s Enabled ALIVE


GPU 3: 430.7 / 427.9 Mh/s | A:175  R:2  HW:0  U:5.35/m

73.5 C  F: 56% 3414 RPM)  E: 950 MHz  M: 825 Mhz  V: 1.175V  A: 99% P: 20%

Last initialised: [2011-09-09 12:11:33]

Thread 3: 214.8 Mh/s Enabled ALIVE

Thread 7: 215.1 Mh/s Enabled ALIVE


Change settings menu:


Code:

Select GPU to change settings on: 0

Temp: 72.0 C

Fan Speed: 50% (4489 RPM)

Engine Clock: 950 MHz

Memory Clock: 825 Mhz

Vddc: 1.175 V

Activity: 99%

Powertune: 20%

Fan autotune is enabled (0-85)

GPU engine clock autotune is enabled (880-950)

Change [A]utomatic [E]ngine [F]an [M]emory [V]oltage [P]owertune

Or press any other key to continue

Settings menu:


Code:

[Q]ueue: 1

[S]cantime: 60

[E]xpiry: 120

[W]rite config file

[C]gminer restart

Display menu:


Code:

[N]ormal [C]lear [S]ilent mode (disable all output)

[D]ebug:off

[P]er-device:off

[Q]uiet:off

[V]erbose:off

[R]PC debug:off

[W]orkTime details:off

co[M]pact: off

[L]og interval:5

[Z]ero statistics

On exiting:


Code:

Summary of runtime statistics:

Started at [2011-07-19 14:40:09]

Runtime: 2 hrs : 31 mins : 18 secs

Average hashrate: 1680.1 Megahash/s

Queued work requests: 3317

Share submissions: 3489

Accepted shares: 3489

Rejected shares: 0

Reject ratio: 0.0

Hardware errors: 0

Efficiency (accepted / queued): 105%

Utility (accepted shares / min): 23.06/min


Discarded work due to new blocks: 0

Stale submissions discarded due to new blocks: 9

Unable to get work from server occasions: 16

Work items generated locally: 330

Submitting work remotely delay occasions: 33

New blocks detected on network: 10


Pool: http://www.guugll.eu:11327

Queued work requests: 3253

Share submissions: 3426

Accepted shares: 3426

Rejected shares: 0

Reject ratio: 0.0

Efficiency (accepted / queued): 105%

Discarded work due to new blocks: 0

Stale submissions discarded due to new blocks: 9

Unable to get work from server occasions: 15

Submitting work remotely delay occasions: 33


Pool: http://www.guugll.eu:11327

Queued work requests: 64

Share submissions: 63

Accepted shares: 63

Rejected shares: 0

Reject ratio: 0.0

Efficiency (accepted / queued): 98%

Discarded work due to new blocks: 0

Stale submissions discarded due to new blocks: 0

Unable to get work from server occasions: 1

Submitting work remotely delay occasions: 0


Summary of per device statistics:


GPU 0: [419.9 Mh/s] [Q:913  A:901  R:0  HW:0  E:99%  U:5.96/m]

GPU 1: [420.1 Mh/s] [Q:912  A:865  R:0  HW:0  E:95%  U:5.72/m]

GPU 2: [420.5 Mh/s] [Q:908  A:865  R:0  HW:0  E:95%  U:5.72/m]

GPU 3: [419.6 Mh/s] [Q:910  A:858  R:0  HW:0  E:94%  U:5.68/m]




Usage instructions:  Run “cgminer –help” to see options:


Usage: . [-atDdGCgIKklmpPQqrRsTouvwOchnV]

Options for both config file and command line:

–api-allow         Allow API access (if enabled) only to the given list of [W:]IP[/Prefix] address[/subnets]

This overrides –api-network and you must specify 127.0.0.1 if it is required

W: in front of the IP address gives that address privileged access to all api commands

–api-description   Description placed in the API status header (default: cgminer version)

–api-groups        API one letter groups G:cmd:cmd[,P:cmd:*...]

See API-README for usage

–api-listen        Listen for API requests (default: disabled)

By default any command that does not just display data returns access denied

See –api-allow to overcome this

–api-network       Allow API (if enabled) to listen on/for any address (default: only 127.0.0.1)

–api-port          Port number of miner API (default: 4028)

–auto-fan          Automatically adjust all GPU fan speeds to maintain a target temperature

–auto-gpu          Automatically adjust all GPU engine clock speeds to maintain a target temperature

–balance           Change multipool strategy from failover to even share balance

–benchmark         Run cgminer in benchmark mode – produces no shares

–compact           Use compact display without per device statistics

–debug|-D          Enable debug output

–device|-d <arg>   Select device to use, one value, range and/or comma separated (e.g. 0-2,4) default: all

–expiry|-E <arg>   Upper bound on how many seconds after getting work we consider a share from it stale (default: 120)

–failover-only     Don’t leak work to backup pools when primary pool is lagging

–fix-protocol      Do not redirect to a different getwork protocol (eg. stratum)

–hotplug <arg>     Set hotplug check time to <arg> seconds (0=never default: 5) – only with libusb

–kernel-path|-K <arg> Specify a path to where bitstream and kernel files are (default: “/usr/local/bin”)

–load-balance      Change multipool strategy from failover to efficiency based balance

–log|-l <arg>      Interval in seconds between log output (default: 5)

—lowmem            Minimise caching of shares for low memory applications

-monitor|-m <arg>  Use custom pipe cmd for output messages

–net-delay         Impose small delays in networking to not overload slow routers

–no-pool-disable   Do not automatically disable pools that continually reject shares

–no-restart        Do not attempt to restart GPUs that hang

–no-submit-stale   Don’t submit shares if they are detected as stale

–pass|-p <arg>     Password for bitcoin JSON-RPC server

–per-device-stats  Force verbose mode and output per-device statistics

–protocol-dump|-P  Verbose dump of protocol-level activities

–queue|-Q <arg>    Minimum number of work items to have queued (0 – 10) (default: 1)

–quiet|-q          Disable logging output, display status and errors

–real-quiet        Disable all output

–remove-disabled   Remove disabled devices entirely, as if they didn’t exist

–retries|-r <arg>  Number of times to retry before giving up, if JSON-RPC call fails (-1 means never) (default: -1)

–retry-pause|-R <arg> Number of seconds to pause, between retries (default: 5)

–rotate <arg>      Change multipool strategy from failover to regularly rotate at N minutes (default: 0)

–round-robin       Change multipool strategy from failover to round robin on failure

–scan-time|-s <arg> Upper bound on time spent scanning current work, in seconds (default: 60)

–sched-start <arg> Set a time of day in HH:MM to start mining (a once off without a stop time)

–sched-stop <arg>  Set a time of day in HH:MM to stop mining (will quit without a start time)

–scrypt            Use the scrypt algorithm for mining (litecoin only)

–sharelog <arg>    Append share log to file

–shares <arg>      Quit after mining N shares (default: unlimited)

–socks-proxy <arg> Set socks4 proxy (host:port)

–syslog            Use system log for output messages (default: standard error)

–temp-cutoff <arg> Temperature where a device will be automatically disabled, one value or comma separated list (default: 95)

–text-only|-T      Disable ncurses formatted screen output

–url|-o <arg>      URL for bitcoin JSON-RPC server

–user|-u <arg>     Username for bitcoin JSON-RPC server

–verbose           Log verbose output to stderr as well as status output

–userpass|-O <arg> Username:Password pair for bitcoin JSON-RPC server

Options for command line only:

–config|-c <arg>   Load a JSON-format configuration file

See example.conf for an example configuration.

–help|-h           Print this message

–version|-V        Display version and exit


GPU only options:


–auto-fan          Automatically adjust all GPU fan speeds to maintain a target temperature

–auto-gpu          Automatically adjust all GPU engine clock speeds to maintain a target temperature

–disable-gpu|-G    Disable GPU mining even if suitable devices exist

–gpu-threads|-g <arg> Number of threads per GPU (1 – 10) (default: 2)

–gpu-dyninterval <arg> Set the refresh interval in ms for GPUs using dynamic intensity (default: 7)

–gpu-engine <arg>  GPU engine (over)clock range in Mhz – one value, range and/or comma separated list (e.g. 850-900,900,750-850)

–gpu-fan <arg>     GPU fan percentage range – one value, range and/or comma separated list (e.g. 25-85,85,65)

–gpu-map <arg>     Map OpenCL to ADL device order manually, paired CSV (e.g. 1:0,2:1 maps OpenCL 1 to ADL 0, 2 to 1)

–gpu-memclock <arg> Set the GPU memory (over)clock in Mhz – one value for all or separate by commas for per card.

–gpu-memdiff <arg> Set a fixed difference in clock speed between the GPU and memory in auto-gpu mode

–gpu-powertune <arg> Set the GPU powertune percentage – one value for all or separate by commas for per card.

–gpu-reorder       Attempt to reorder GPU devices according to PCI Bus ID

–gpu-vddc <arg>    Set the GPU voltage in Volts – one value for all or separate by commas for per card.

–intensity|-I <arg> Intensity of GPU scanning (d or -10 -> 10, default: d to maintain desktop interactivity)

–kernel|-k <arg>   Override kernel to use (diablo, poclbm, phatk or diakgcn) – one value or comma separated

–ndevs|-n          Enumerate number of detected GPUs and exit

–temp-hysteresis <arg> Set how much the temperature can fluctuate outside limits when automanaging speeds (default: 3)

–temp-overheat <arg> Overheat temperature when automatically managing fan and GPU speeds (default: 85)

–temp-target <arg> Target temperature when automatically managing fan and GPU speeds (default: 75)

–vectors|-v <arg>  Override detected optimal vector (1, 2 or 4) – one value or comma separated list

–worksize|-w <arg> Override detected optimal worksize – one value or comma separated list


SCRYPT only options:


–lookup-gap <arg>  Set GPU lookup gap for scrypt mining, comma separated

–thread-concurrency <arg> Set GPU thread concurrency for scrypt mining, comma separated


See SCRYPT-README for more information regarding litecoin mining.


Cgminer will automatically find all of your Avalon ASIC, BFL ASIC, BitForce

FPGAs, Icarus bitstream FPGAs, ModMiner FPGAs, or Ztex FPGAs


ASIC and FPGA mining boards (Avalon, BFL ASIC, BitForce, Icarus, ModMiner, Ztex)

only options:


–avalon-options <arg> Set avalon options baud:miners:asic:timeout:freq

–avalon-temp <arg> Set avalon target temperature (default: 45)

–bfl-range         Use nonce range on bitforce devices if supported

–icarus-options <arg> Set specific FPGA board configurations – one set of values for all or comma separated

–icarus-timing <arg> Set how the Icarus timing is calculated – one setting/value for all or comma separated

–usb <arg>         USB device selection (See below)

–usb-dump          (See FPGA-README)


For other ASIC details see the ASIC-README

For other FPGA details see the FPGA-README



EXECUTIVE SUMMARY ON USAGE:


After saving configuration from the menu, you do not need to give cgminer any

arguments and it will load your configuration.


Any configuration file may also contain a single

“include” : “filename”

to recursively include another configuration file.

Writing the configuration will save all settings from all files in the output.


Single FTC pool, regular desktop:


cgminer -o http://www.guugll.eu:11327 -u username -p password


Single FTC pool, dedicated miner:


cgminer -o http://www.guugll.eu:11327 -u username -p password -I 9


Single FTC pool, first card regular desktop, 3 other dedicated cards:


cgminer -o http://www.guugll.eu:11327 -u username -p password -I d,9,9,9


Multiple FTC pool, dedicated miner:


cgminer -o http://www.guugll.eu:11327 -u pool1username -p pool1password -o http://p2pool.org:9377 -u pool2usernmae -p pool2password -I 9


Add overclocking settings, GPU and fan control for all cards:


cgminer -o http://www.guugll.eu:11327 -u username -p password -I 9 –auto-fan –auto-gpu –gpu-engine 750-950 –gpu-memclock 300


Add overclocking settings, GPU and fan control with different engine settings for 4 cards:


cgminer -o http://www.guugll.eu:11327 -u username -p password -I 9 –auto-fan –auto-gpu –gpu-engine 750-950,945,700-930,960 –gpu-memclock 300


READ WARNINGS AND DOCUMENTATION BELOW ABOUT OVERCLOCKING


On Linux you virtually always need to export your display settings before

starting to get all the cards recognised and/or temperature+clocking working:


export DISPLAY=:0



WHILE RUNNING:


The following options are available while running with a single keypress:


[P]ool management [G]PU management [ S]ettings [D]isplay options [Q]uit


P gives you:


Current pool management strategy: Failover

[A]dd pool [R]emove pool [D]isable pool [E]nable pool

[C]hange management strategy [ S]witch pool [ I]nformation


S gives you:


[Q]ueue: 1

[ S]cantime: 60

[E]xpiry: 120

[R]etries: -1

[P]ause: 5

[W]rite config file


D gives you:


Toggle: [D]ebug [N]ormal [ S]ilent [V]erbose [R]PC debug

[L]og interval [C]lear


Q quits the application.


G gives you something like:


GPU 0: [124.2 / 191.3 Mh/s] [Q:212  A:77  R:33  HW:0  E:36%  U:1.73/m]

Temp: 67.0 C

Fan Speed: 35% (2500 RPM)

Engine Clock: 960 MHz

Memory Clock: 480 Mhz

Vddc: 1.200 V

Activity: 93%

Powertune: 0%

Last initialised: [2011-09-06 12:03:56]

Thread 0: 62.4 Mh/s Enabled ALIVE

Thread 1: 60.2 Mh/s Enabled ALIVE


[E]nable [D]isable [R]estart GPU [C]hange settings

Or press any other key to continue




Also many issues and FAQs are covered in the forum thread

dedicated to this program,
http://forum.bitcoin.org/index.php?topic=28402.0


The output line shows the following:

(5s):1713.6 (avg):1707.8 Mh/s | Q:301  A:729  R:8  HW:0  E:242%  U:22.53/m


Each column is as follows:

5s:  A 5 second exponentially decaying average hash rate

avg: An all time average hash rate

Q:   The number of requested (Queued) work items from the pools

A:   The number of Accepted shares

R:   The number of Rejected shares

HW:  The number of HardWare errors

E:   The Efficiency defined as number of shares returned / work item

U:   The Utility defined as the number of shares / minute


GPU 1: 73.5C 2551RPM | 427.3/443.0Mh/s | A:8 R:0 HW:0 U:4.39/m


Each column is as follows:

Temperature (if supported)

Fanspeed (if supported)

A 5 second exponentially decaying average hash rate

An all time average hash rate

The number of accepted shares

The number of rejected shares

The number of hardware erorrs

The utility defines as the number of shares / minute


The cgminer status line shows:

TQ: 1  ST: 1  SS: 0  DW: 0  NB: 1  LW: 8  GF: 1  RF: 1


TQ is Total Queued work items.

ST is STaged work items (ready to use).

SS is Stale Shares discarded (detected and not submitted so don’t count as rejects)

DW is Discarded Work items (work from block no longer valid to work on)

NB is New Blocks detected on the network

LW is Locally generated Work items

GF is Getwork Fail Occasions (server slow to provide work)

RF is Remote Fail occasions (server slow to accept work)


NOTE: Running intensities above 9 with current hardware is likely to only

diminish return performance even if the hash rate might appear better. A good

starting baseline intensity to try on dedicated miners is 9. Higher values are

there to cope with future improvements in hardware.




MULTIPOOL


FAILOVER STRATEGIES WITH MULTIPOOL:

A number of different strategies for dealing with multipool setups are

available. Each has their advantages and disadvantages so multiple strategies

are available by user choice, as per the following list:


FAILOVER:

The default strategy is failover. This means that if you input a number of

pools, it will try to use them as a priority list, moving away from the 1st

to the 2nd, 2nd to 3rd and so on. If any of the earlier pools recover, it will

move back to the higher priority ones.


ROUND ROBIN:

This strategy only moves from one pool to the next when the current one falls

idle and makes no attempt to move otherwise.


ROTATE:

This strategy moves at user-defined intervals from one active pool to the next,

skipping pools that are idle.


LOAD BALANCE:

This strategy sends work to all the pools to maintain optimum load. The most

efficient pools will tend to get a lot more shares. If any pool falls idle, the

rest will tend to take up the slack keeping the miner busy.


BALANCE:

This strategy monitors the amount of difficulty 1 shares solved for each pool

and uses it to try to end up doing the same amount of work for all pools.




LOGGING


cgminer will log to stderr if it detects stderr is being redirected to a file.

To enable logging simply add 2>logfile.txt to your command line and logfile.txt

will contain the logged output at the log level you specify (normal, verbose,

debug etc.)


In other words if you would normally use:

./cgminer -o xxx -u yyy -p zzz

if you use

./cgminer -o xxx -u yyy -p zzz 2>logfile.txt

it will log to a file called logfile.txt and otherwise work the same.


There is also the -m option on linux which will spawn a command of your choice

and pipe the output directly to that command.


If you start cgminer with the –sharelog option, you can get detailed

information for each share found. The argument to the option may be “-” for

standard output (not advisable with the ncurses UI), any valid positive number

for that file descriptor, or a filename.


To log share data to a file named “share.log”, you can use either:

./cgminer –sharelog 50 -o xxx -u yyy -p zzz 50>share.log

./cgminer –sharelog share.log -o xxx -u yyy -p zzz


For every share found, data will be logged in a CSV (Comma Separated Value)

format:

timestamp,disposition,target,pool,dev,thr,sharehash,sharedata

For example (this is wrapped, but it’s all on one line for real):

1335313090,reject,

ffffffffffffffffffffffffffffffffffffffffffffffffffffffff00000000,


http://localhost:8337,GPU0,0,


6f983c918f3299b58febf95ec4d0c7094ed634bc13754553ec34fc3800000000,

00000001a0980aff4ce4a96d53f4b89a2d5f0e765c978640fe24372a000001c5

000000004a4366808f81d44f26df3d69d7dc4b3473385930462d9ab707b50498

f681634a4f1f63d01a0cd43fb338000000000080000000000000000000000000

0000000000000000000000000000000000000000000000000000000080020000




OVERCLOCKING WARNING AND INFORMATION


AS WITH ALL OVERCLOCKING TOOLS YOU ARE ENTIRELY RESPONSIBLE FOR ANY HARM YOU

MAY CAUSE TO YOUR HARDWARE. OVERCLOCKING CAN INVALIDATE WARRANTIES, DAMAGE

HARDWARE AND EVEN CAUSE FIRES. THE AUTHOR ASSUMES NO RESPONSIBILITY FOR ANY

DAMAGE YOU MAY CAUSE OR UNPLANNED CHILDREN THAT MAY OCCUR AS A RESULT.


The GPU monitoring, clocking and fanspeed control incorporated into cgminer

comes through use of the ATI Display Library. As such, it only supports ATI

GPUs. Even if ADL support is successfully built into cgminer, unless the card

and driver supports it, no GPU monitoring/settings will be available.


Cgminer supports initial setting of GPU engine clock speed, memory clock

speed, voltage, fanspeed, and the undocumented powertune feature of 69×0+ GPUs.

The setting passed to cgminer is used by all GPUs unless separate values are

specified. All settings can all be changed within the menu on the fly on a

per-GPU basis.


For example:

–gpu-engine 950 –gpu-memclock 825


will try to set all GPU engine clocks to 950 and all memory clocks to 825,

while:

–gpu-engine 950,945,930,960 –gpu-memclock 300


will try to set the engine clock of card 0 to 950, 1 to 945, 2 to 930, 3 to

960 and all memory clocks to 300.


AUTO MODES:

There are two “auto” modes in cgminer, –auto-fan and –auto-gpu. These can

be used independently of each other and are complementary. Both auto modes

are designed to safely change settings while trying to maintain a target

temperature. By default this is set to 75 degrees C but can be changed with:


–temp-target

e.g.

–temp-target 80

Sets all cards’ target temperature to 80 degrees.


–temp-target 75,85

Sets card 0 target temperature to 75, and card 1 to 85 degrees.


AUTO FAN:

e.g.

–auto-fan (implies 85% upper limit)

–gpu-fan 25-85,65 –auto-fan


Fan control in auto fan works off the theory that the minimum possible fan

required to maintain an optimal temperature will use less power, make less

noise, and prolong the life of the fan. In auto-fan mode, the fan speed is

limited to 85% if the temperature is below “overheat” intentionally, as

higher fanspeeds on GPUs do not produce signficantly more cooling, yet

significanly shorten the lifespan of the fans. If temperature reaches the

overheat value, fanspeed will still be increased to 100%. The overheat value

is set to 85 degrees by default and can be changed with:


–temp-overheat

e.g.

–temp-overheat 75,85

Sets card 0 overheat threshold to 75 degrees and card 1 to 85.


AUTO GPU:

e.g.

–auto-gpu –gpu-engine 750-950

–auto-gpu –gpu-engine 750-950,945,700-930,960


GPU control in auto gpu tries to maintain as high a clock speed as possible

while not reaching overheat temperatures. As a lower clock speed limit,

the auto-gpu mode checks the GPU card’s “normal” clock speed and will not go

below this unless you have manually set a lower speed in the range. Also,

unless a higher clock speed was specified at startup, it will not raise the

clockspeed. If the temperature climbs, fanspeed is adjusted and optimised

before GPU engine clockspeed is adjusted. If fan speed control is not available

or already optimal, then GPU clock speed is only decreased if it goes over

the target temperature by the hysteresis amount, which is set to 3 by default

and can be changed with:

–temp-hysteresis

If the temperature drops below the target temperature, and engine clock speed

is not at the highest level set at startup, cgminer will raise the clock speed.

If at any time you manually set an even higher clock speed successfully in

cgminer, it will record this value and use it as its new upper limit (and the

same for low clock speeds and lower limits). If the temperature goes over the

cutoff limit (95 degrees by default), cgminer will completely disable the GPU

from mining and it will not be re-enabled unless manually done so. The cutoff

temperature can be changed with:


–temp-cutoff

e.g.

–temp-cutoff 95,105

Sets card 0 cutoff temperature to 95 and card 1 to 105.


–gpu-memdiff -125

This setting will modify the memory speed whenever the GPU clock speed is

modified by –auto-gpu. In this example, it will set the memory speed to

be 125 Mhz lower than the GPU speed. This is useful for some cards like the

6970 which normally don’t allow a bigger clock speed difference.


CHANGING SETTINGS:

When setting values, it is important to realise that even though the driver

may report the value was changed successfully, and the new card power profile

information contains the values you set it to, that the card itself may

refuse to use those settings. As the performance profile changes dynamically,

querying the “current” value on the card can be wrong as well. So when changing

values in cgminer, after a pause of 1 second, it will report to you the current

values where you should check that your change has taken. An example is that

6970 reference cards will accept low memory values but refuse to actually run

those lower memory values unless they’re within 125 of the engine clock speed.

In that scenario, they usually set their real speed back to their default.


Cgminer reports the so-called “safe” range of whatever it is you are modifying

when you ask to modify it on the fly. However, you can change settings to values

outside this range. Despite this, the card can easily refuse to accept your

changes, or worse, to accept your changes and then silently ignore them. So

there is absolutely to know how far to/from where/to it can set things safely or

otherwise, and there is nothing stopping you from at least trying to set them

outside this range. Being very conscious of these possible failures is why

cgminer will report back the current values for you to examine how exactly the

card has responded. Even within the reported range of accepted values by the

card, it is very easy to crash just about any card, so it cannot use those

values to determine what range to set. You have to provide something meaningful

manually for cgminer to work with through experimentation.


STARTUP / SHUTDOWN:

When cgminer starts up, it tries to read off the current profile information

for clock and fan speeds and stores these values. When quitting cgminer, it

will then try to restore the original values. Changing settings outside of

cgminer while it’s running may be reset to the startup cgminer values when

cgminer shuts down because of this.



RPC API


For RPC API details see the API-README file



GPU DEVICE ISSUES and use of –gpu-map


GPUs mine with OpenCL software via the GPU device driver. This means you need

to have both an OpenCL SDK installed, and the GPU device driver RUNNING (i.e.

Xorg up and running configured for all devices that will mine on linux etc.)

Meanwhile, the hardware monitoring that cgminer offers for AMD devices relies

on the ATI Display Library (ADL) software to work. OpenCL DOES NOT TALK TO THE

ADL. There is no 100% reliable way to know that OpenCL devices are identical

to the ADL devices, as neither give off the same information. cgminer does its

best to correlate these devices based on the order that OpenCL and ADL numbers

them. It is possible that this will fail for the following reasons:


1. The device order is listed differently by OpenCL and ADL (rare), even if the

number of devices is the same.

2. There are more OpenCL devices than ADL. OpenCL stupidly sees one GPU as two

devices if you have two monitors connected to the one GPU.

3. There are more ADL devices than OpenCL. ADL devices include any ATI GPUs,

including ones that can’t mine, like some older R4xxx cards.


To cope with this, the ADVANCED option for –gpu-map is provided with cgminer.

DO NOT USE THIS UNLESS YOU KNOW WHAT YOU ARE DOING. The default will work the

vast majority of the time unless you know you have a problem already.


To get useful information, start cgminer with just the -n option. You will get

output that looks like this:


[2012-04-25 13:17:34] CL Platform 0 vendor: Advanced Micro Devices, Inc.

[2012-04-25 13:17:34] CL Platform 0 name: AMD Accelerated Parallel Processing

[2012-04-25 13:17:34] CL Platform 0 version: OpenCL 1.1 AMD-APP (844.4)

[2012-04-25 13:17:34] Platform 0 devices: 3

[2012-04-25 13:17:34]   0       Tahiti

[2012-04-25 13:17:34]   1       Tahiti

[2012-04-25 13:17:34]   2       Cayman

[2012-04-25 13:17:34] GPU 0 AMD Radeon HD 7900 Series  hardware monitoring enabled

[2012-04-25 13:17:34] GPU 1 AMD Radeon HD 7900 Series  hardware monitoring enabled

[2012-04-25 13:17:34] GPU 2 AMD Radeon HD 6900 Series hardware monitoring enabled

[2012-04-25 13:17:34] 3 GPU devices max detected


Note the number of devices here match, and the order is the same. If devices 1

and 2 were different between Tahiti and Cayman, you could run cgminer with:

–gpu-map 2:1,1:2

And it would swap the monitoring it received from ADL device 1 and put it to

opencl device 2 and vice versa.


If you have 2 monitors connected to the first device it would look like this:


[2012-04-25 13:17:34] Platform 0 devices: 4

[2012-04-25 13:17:34]   0       Tahiti

[2012-04-25 13:17:34]   1       Tahiti

[2012-04-25 13:17:34]   2       Tahiti

[2012-04-25 13:17:34]   3       Cayman

[2012-04-25 13:17:34] GPU 0 AMD Radeon HD 7900 Series  hardware monitoring enabled

[2012-04-25 13:17:34] GPU 1 AMD Radeon HD 7900 Series  hardware monitoring enabled

[2012-04-25 13:17:34] GPU 2 AMD Radeon HD 6900 Series hardware monitoring enabled


To work around this, you would use:

-d 0 -d 2 -d 3 –gpu-map 2:1,3:2


If you have an older card as well as the rest it would look like this:


[2012-04-25 13:17:34] Platform 0 devices: 3

[2012-04-25 13:17:34]   0       Tahiti

[2012-04-25 13:17:34]   1       Tahiti

[2012-04-25 13:17:34]   2       Cayman

[2012-04-25 13:17:34] GPU 0 AMD Radeon HD 4500 Series  hardware monitoring enabled

[2012-04-25 13:17:34] GPU 1 AMD Radeon HD 7900 Series  hardware monitoring enabled

[2012-04-25 13:17:34] GPU 2 AMD Radeon HD 7900 Series  hardware monitoring enabled

[2012-04-25 13:17:34] GPU 3 AMD Radeon HD 6900 Series hardware monitoring enabled


To work around this you would use:

–gpu-map 0:1,1:2,2:3



FAQ


Q: cgminer segfaults when I change my shell window size.

A: Older versions of libncurses have a bug to do with refreshing a window

after a size change. Upgrading to a new version of curses will fix it.


Q: Can I mine on servers from different networks (eg smartcoin and bitcoin) at

the same time?

A: No, cgminer keeps a database of the block it’s working on to ensure it does

not work on stale blocks, and having different blocks from two networks would

make it invalidate the work from each other.


Q: Can I change the intensity settings individually for each GPU?

A: Yes, pass a list separated by commas such as -I d,4,9,9


Q: Can I put multiple pools in the config file?

A: Yes, check the example.conf file. Alternatively, set up everything either on

the command line or via the menu after startup and choose settings->write

config file and the file will be loaded one each startup.


Q: The build fails with gcc is unable to build a binary.

A: Remove the “-march=native” component of your CFLAGS as your version of gcc

does not support it.


Q: The CPU usage is high.

A: The ATI drivers after 11.6 have a bug that makes them consume 100% of one

CPU core unnecessarily so downgrade to 11.6. Binding cgminer to one CPU core on

windows can minimise it to 100% (instead of more than one core). Driver version

11.11 on linux and 11.12 on windows appear to have fixed this issue. Note that

later drivers may have an apparent return of high CPU usage. Try

‘export GPU_USE_SYNC_OBJECTS=1′ on Linux before starting cgminer. You can also

set this variable in windows via a batch file or on the command line before

starting cgminer with ‘setx GPU_USE_SYNC_OBJECTS 1′


Q: Can you implement feature X?

A: I can, but time is limited, and people who donate are more likely to get

their feature requests implemented.


Q: My GPU hangs and I have to reboot it to get it going again?

A: The more aggressively the mining software uses your GPU, the less overclock

you will be able to run. You are more likely to hit your limits with cgminer

and you will find you may need to overclock your GPU less aggressively. The

software cannot be responsible and make your GPU hang directly. If you simply

cannot get it to ever stop hanging, try decreasing the intensity, and if even

that fails, try changing to the poclbm kernel with -k poclbm, though you will

sacrifice performance. cgminer is designed to try and safely restart GPUs as

much as possible, but NOT if that restart might actually crash the rest of the

GPUs mining, or even the machine. It tries to restart them with a separate

thread and if that separate thread dies, it gives up trying to restart any more

GPUs.


Q: Work keeps going to my backup pool even though my primary pool hasn’t

failed?

A: Cgminer checks for conditions where the primary pool is lagging and will

pass some work to the backup servers under those conditions. The reason for

doing this is to try its absolute best to keep the GPUs working on something

useful and not risk idle periods. You can disable this behaviour with the

option –failover-only.


Q: Is this a virus?

A: Cgminer is being packaged with other trojan scripts and some antivirus

software is falsely accusing cgminer.exe as being the actual virus, rather

than whatever it is being packaged with. If you installed cgminer yourself,

then you do not have a virus on your computer. Complain to your antivirus

software company. They seem to be flagging even source code now from cgminer

as viruses, even though text source files can’t do anything by themself.


Q: Can you modify the display to include more of one thing in the output and

less of another, or can you change the quiet mode or can you add yet another

output mode?

A: Everyone will always have their own view of what’s important to monitor.

The defaults are very sane and I have very little interest in changing this

any further.


Q: Can you change the autofan/autogpu to change speeds in a different manner?

A: The defaults are sane and safe. I’m not interested in changing them

further. The starting fan speed is set to 50% in auto-fan mode as a safety

precaution.


Q: What are the best parameters to pass for X pool/hardware/device.

A: Virtually always, the DEFAULT parameters give the best results. Most user

defined settings lead to worse performance. The ONLY thing most users should

need to set is the Intensity.


Q: What happened to CPU mining?

A: Being increasingly irrelevant for most users, and a maintenance issue, it is

no longer under active development and will not be supported. No binary builds

supporting CPU mining will be released. Virtually all remaining users of CPU

mining are as back ends for illegal botnets.


Q: I upgraded cgminer version and my hashrate suddenly dropped!

A: No, you upgraded your SDK version unwittingly between upgrades of cgminer

and that caused  your hashrate to drop. See the next question.


Q: I upgraded my ATI driver/SDK/cgminer and my hashrate suddenly dropped!

A: The hashrate performance in cgminer is tied to the version of the ATI SDK

that is installed only for the very first time cgminer is run. This generates

binaries that are used by the GPU every time after that. Any upgrades to the

SDK after that time will have no effect on the binaries. However, if you

install a fresh version of cgminer, and have since upgraded your SDK, new

binaries will be built. It is known that the 2.6 ATI SDK has a huge hashrate

penalty on generating new binaries. It is recommended to not use this SDK at

this time unless you are using an ATI 7xxx card that needs it.


Q: Which AMD SDK is the best for cgminer?

A: At the moment, versions 2.4 and 2.5 work the best for R5xxx and R6xxx GPUS.

SDK 2.6 or 2.7 works best for R7xxx. SDK 2.8 is known to have many problems.

If you are need to use the 2.6+ SDK or R7xxx or later, the phatk kernel will

perform poorly, while the diablo or my custom modified poclbm kernel are

optimised for it.


Q: Which AMD driver is the best?

A: Unfortunately AMD has a history of having quite a few releases with issues

when it comes to mining, either in terms of breaking mining, increasing CPU

usage or very low hashrates. Only experimentation can tell you for sure, but

some good releases were 11.6, 11.12, 12.4 and 12.8. Note that older cards may

not work with the newer drivers.


Q: I have multiple SDKs installed, can I choose which one it uses?

A: Run cgminer with the -n option and it will list all the platforms currently

installed. Then you can tell cgminer which platform to use with –gpu-platform.


Q: GUI version?

A: No. The RPC interface makes it possible for someone else to write one

though.


Q: I’m having an issue. What debugging information should I provide?

A: Start cgminer with your regular commands and add -D -T –verbose and provide

the full startup output and a summary of your hardware, operating system, ATI

driver version and ATI stream version.


Q: cgminer reports no devices or only one device on startup on Linux although

I have multiple devices and drivers+SDK installed properly?

A: Try “export DISPLAY=:0″ before running cgminer.


Q: cgminer crashes immediately on startup.

A: One of the common reasons for this is that you have mixed files on your

machine for the driver or SDK. Windows has a nasty history of not cleanly

uninstalling files so you may have to use third party tools like driversweeper

to remove old versions. The other common reason for this is windows

antivirus software is disabling one of the DLLs from working. If cgminer

starts with the -T option but never starts without it, this is a sure fire

sign you have this problem and will have to disable your antivirus or make

exceptions.


Q: Why don’t you provide win64 builds?

A: Win32 builds work everywhere and there is precisely zero advantage to a

64 bit build on windows.


Q: Is it faster to mine on windows or linux?

A: It makes no difference. It comes down to choice of operating system for

their various features. Linux offers much better long term stability and

remote monitoring and security, while windows offers you overclocking tools

that can achieve much more than cgminer can do on linux.


Q: Can I mine with cgminer on a MAC?

A: cgminer will compile on OSX, but the performance of GPU mining is

compromised due to the opencl implementation on OSX, there is no temperature

or fanspeed monitoring, and the cooling design of most MACs, despite having

powerful GPUs, will usually not cope with constant usage leading to a high

risk of thermal damage. It is highly recommended not to mine on a MAC unless

it is to a USB device.


Q: Cgminer cannot see any of my GPUs even though I have configured them all

to be enabled and installed OpenCL (+/- Xorg is running and the DISPLAY

variable is exported on linux)?

A: Check the output of ‘cgminer -n’, it will list what OpenCL devices your

installed SDK recognises. If it lists none, you have a problem with your

version or installation of the SDK.


Q: Cgminer is mining on the wrong GPU, I want it on the AMD but it’s mining

on my on board GPU?

A: Make sure the AMD OpenCL SDK is installed, check the output of ‘cgminer -n’

and use the appropriate parameter with –gpu-platform.


Q: I’m getting much lower hashrates than I should be for my GPU?

A: Look at your driver/SDK combination and disable power saving options for

your GPU. Specifically look to disable ULPS. Make sure not to set intensity

above 11 for BTC mining.


Q: Can I mine with AMD while running Nvidia or Intel GPUs at the same time?

A: If you can install both drivers successfully (easier on windows) then

yes, using the –gpu-platform option.


Q: Can I mine with Nvidia or Intel GPUs?

A: Yes but their hashrate is very poor and likely you’ll be using much more

energy than you’ll be earning in coins.


Q: Can I mine on both Nvidia and AMD GPUs at the same time?

A: No, you must run one instance of cgminer with the –gpu-platform option for

each.


Q: Can I mine on Linux without running Xorg?

A: With Nvidia you can, but with AMD you cannot.


Q: I’m trying to mine litecoin but cgminer shows MH values instead of kH and

submits no shares?

A: Add the –scrypt parameter.


Q: I can’t get anywhere near enough hashrate for scrypt compared to other

people?

A: You may not have enough system RAM as this is also required.


Q: My scrypt hashrate is high but the pool reports only a tiny proportion of

my hashrate?

A: You are generating garbage hashes due to your choice of settings. Your

Work Utility (WU) value will confirm you are not generating garbage. You

should be getting about .9WU per kHash. If not, then try decreasing your

intensity, do not increase the number of gpu-threads, and consider adding

system RAM to match your GPU ram. You may also be using a bad combination

of driver and/or SDK.


Q: Scrypt fails to initialise the kernel every time?

A: Your parameters are too high. Don’t add GPU threads, don’t set intensity

too high, decrease thread concurrency. See the SCRYPT-README for a lot more

help.


Q: Cgminer stops mining (or my GPUs go DEAD) and I can’t close it?

A: Once the driver has crashed, there is no way for cgminer to close cleanly.

You will have to kill it, and depending on how corrupted your driver state

has gotten, you may even need to reboot. Windows is known to reset drivers

when they fail and cgminer will be stuck trying to use the old driver instance.


Q: I can’t get any monitoring of temperatures or fanspeed with cgminer when

I start it remotely?

A: With linux, make sure to export the DISPLAY variable. On windows, you

cannot access these monitoring values via RDP. This should work with tightVNC

or teamviewer though.


Q: I change my GPU engine/memory/voltage and cgminer reports back no change?

A: Cgminer asks the GPU using the ATI Display Library to change settings, but

the driver and hardware are free to do what it wants with that query, including

ignoring it. Some GPUs are locked with one or more of those properties as well.


Q: I have multiple GPUs and although many devices show up, it appears to be

working only on one GPU splitting it up.

A: Your driver setup is failing to properly use the accessory GPUs. Your

driver may be configured wrong or you have a driver version that needs a dummy

plug on all the GPUs that aren’t connected to a monitor.


Q: Should I use crossfire/SLI?

A: It does not benefit mining at all and depending on the GPU may actually

worsen performance.


Q: I have some random GPU performance related problem not addressed above.

A: Seriously, it’s the driver and/or SDK. Uninstall them and start again,

noting there is no clean way to uninstall them so you have to use extra tools

or do it manually.


Q: Do I need to recompile after updating my driver/SDK?

A: No. The software is unchanged regardless of which driver/SDK/ADL_SDK version

you are running. However if you change SDKs you should delete any generated

.bin files for them to be recreated with the new SDK.


Q: I switch users on windows and my mining stops working?

A: That’s correct, it does. It’s a permissions issue that there is no known

fix for due to monitoring of GPU fanspeeds and temperatures. If you disable

the monitoring with –no-adl it should switch okay.


Q: My network gets slower and slower and then dies for a minute?

A; Try the –net-delay option.


Q: How do I tune for p2pool?

A: p2pool has very rapid expiration of work and new blocks, it is suggested you

decrease intensity by 1 from your optimal value, and decrease GPU threads to 1

with -g 1. It is also recommended to use –failover-only since the work is

effectively like a different block chain. If mining with a minirig, it is worth

adding the –bfl-range option.


Q: Are OpenCL kernels from other mining software useable in cgminer?

A: No, the APIs are slightly different between the different software and they

will not work.


Q: I run PHP on windows to access the API with the example miner.php. Why does

it fail when php is installed properly but I only get errors about Sockets not

working in the logs?

A: http://us.php.net/manual/en/sockets.installation.php


Q: What is a PGA?

A: At the moment, cgminer supports 4 FPGAs: BitForce, Icarus, ModMiner, and Ztex.

They are Field-Programmable Gate Arrays that have been programmed to do Bitcoin

mining. Since the acronym needs to be only 3 characters, the “Field-” part has

been skipped.


Q: How do I get my BFL/Icarus/Lancelot/Cairnsmore device to auto-recognise?

A: On linux, if the /dev/ttyUSB* devices don’t automatically appear, the only

thing that needs to be done is to load the driver for them:

BFL: sudo modprobe ftdi_sio vendor=0×0403 product=0×6014

Icarus: sudo modprobe pl2303 vendor=0x067b product=0×230

Lancelot: sudo modprobe ftdi_sio vendor=0×0403 product=0×6001

Cairnsmore: sudo modprobe ftdi_sio product=0×8350 vendor=0×0403

On windows you must install the pl2303 or ftdi driver required for the device

pl2303: http://prolificusa.com/pl-2303hx-drivers/

ftdi: http://www.ftdichip.com/Drivers/VCP.htm


Q: On linux I can see the /dev/ttyUSB* devices for my Icarus FPGAs, but

cgminer can’t mine on them

A: Make sure you have the required priviledges to access the /dev/ttyUSB* devices:

sudo ls -las /dev/ttyUSB*

will give output like:

0 crw-rw—- 1 root dialout 188, 0 2012-09-11 13:49 /dev/ttyUSB0

This means your account must have the group ‘dialout’ or root priviledges

To permanently give your account the ‘dialout’ group:

sudo usermod -G dialout -a `whoami`

Then logout and back in again


Q: Can I mine scrypt with FPGAs or ASICs?

A: No.


Q: What is stratum and how do I use it?

A: Stratum is a protocol designed for pooled mining in such a way as to

minimise the amount of network communications, yet scale to hardware of any

speed. With versions of cgminer 2.8.0+, if a pool has stratum support, cgminer

will automatically detect it and switch to the support as advertised if it can.

If you input the stratum port directly into your configuration, or use the

special prefix “stratum+tcp://” instead of “http://”, cgminer will ONLY try to

use stratum protocol mining. The advantages of stratum to the miner are no

delays in getting more work for the miner, less rejects across block changes,

and far less network communications for the same amount of mining hashrate. If

you do NOT wish cgminer to automatically switch to stratum protocol even if it

is detected, add the –fix-protocol option.


Q: Why don’t the statistics add up: Accepted, Rejected, Stale, Hardware Errors,

Diff1 Work, etc. when mining greater than 1 difficulty shares?

A: As an example, if you look at ‘Difficulty Accepted’ in the RPC API, the number

of difficulty shares accepted does not usually exactly equal the amount of work

done to find them. If you are mining at 8 difficulty, then you would expect on

average to find one 8 difficulty share, per 8 single difficulty shares found.

However, the number is actually random and converges over time, it is an average,

not an exact value, thus you may find more or less than the expected average.


Q: Why do the scrypt diffs not match with the current difficulty target?

A: The current scrypt block difficulty is expressed in terms of how many

multiples of the BTC difficulty it currently is (eg 28) whereas the shares of

“difficulty 1″ are actually 65536 times smaller than the BTC ones. The diff

expressed by cgminer is as multiples of difficulty 1 shares.



This code is provided entirely free of charge by the programmer in his spare

time so donations would be greatly appreciated. Please consider donating to the

address below.


Con Kolivas <kernel@kolivas.org>

15qSxP1SQcUX3o4nhkfdbgyoWEFMomJ4rZ


 


source: https://bitcointalk.org/index.php?topic=28402.0



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