Topic: OFFICIAL CGMINER mining software thread for linux/win/osx/mips/arm/r-pi 4.11.0 - page 466. (Read 5806015 times)
October 16, 2012, 12:16:07 AM
I need scrypt parameters for mining with gtx 680
October 15, 2012, 11:09:35 PM
i want to mine on litecoin which version i donwload and how to use it
thanks
What are you mining on?thanks
on pool-x using cpuminer
October 15, 2012, 10:54:25 PM
Code:
[2012-10-15 01:31:50] Pool 7 http://api.bitcoin.cz:8332 not responding!
[2012-10-15 01:31:51] Pool 7 http://api.bitcoin.cz:8332 alive
I don't know if it happens every time the pool doesn't respond for a while, or whenever my box changes its IP address. I'm just sure it happens at least every few hours.
HTH.
I haven't seen this myself but there could well still be a bug in there. I'll keep auditing code.
October 15, 2012, 10:11:39 PM
i want to mine on litecoin which version i donwload and how to use it
thanks
What are you mining on? thanks
October 15, 2012, 09:12:39 PM
i want to mine on litecoin which version i donwload and how to use it
thanks
thanks
October 15, 2012, 08:38:18 PM
Nice, but it doesn't actually achieve any demonstrable performance advantage.
October 15, 2012, 08:22:31 PM
That's still only accounting for the simultaneous nonce problem, not the similar bitmask or zero bitmask cases. You certainly make a good argument for not using atomic ops.
No bitmasking needed, the C "?" operator has a specific GPU ISA op code.
Quote
OCL: (phatk vectors 2 example)
(...)
#elif defined VECTORS2
uint result = W[117].x ? 0u:W[3].x; //if(!W[117].x) result=W[3].x; else result=0;
result = W[117].y ? result:W[3].y; //if(!W[117].y) result=W[3].y; /*else result=result;*/
if (result) //result can only be 0 or a nonce: W[3].x or W[3].y
SETFOUND(result);
(...)
GPU ISA:
(...)
1349 z: ADD_INT T3.z, PV1348.x, T0.x
w: ADD_INT ____, PV1348.y, T0.w
1350 y: CNDE_INT ____, PV1349.w, R18.w, 0.0f
1351 x: CNDE_INT R2.x, T3.z, R17.z, PV1350.y
1352 x: PREDNE_INT ____, R2.x, 0.0f UPDATE_EXEC_MASK UPDATE_PRED
66 JUMP POP_CNT(1) ADDR(76)
(...)
(...)
#elif defined VECTORS2
uint result = W[117].x ? 0u:W[3].x; //if(!W[117].x) result=W[3].x; else result=0;
result = W[117].y ? result:W[3].y; //if(!W[117].y) result=W[3].y; /*else result=result;*/
if (result) //result can only be 0 or a nonce: W[3].x or W[3].y
SETFOUND(result);
(...)
GPU ISA:
(...)
1349 z: ADD_INT T3.z, PV1348.x, T0.x
w: ADD_INT ____, PV1348.y, T0.w
1350 y: CNDE_INT ____, PV1349.w, R18.w, 0.0f
1351 x: CNDE_INT R2.x, T3.z, R17.z, PV1350.y
1352 x: PREDNE_INT ____, R2.x, 0.0f UPDATE_EXEC_MASK UPDATE_PRED
66 JUMP POP_CNT(1) ADDR(76)
(...)
October 15, 2012, 07:48:41 PM
That's still only accounting for the simultaneous nonce problem, not the similar bitmask or zero bitmask cases. You certainly make a good argument for not using atomic ops.
October 15, 2012, 07:15:37 PM
Don't forget modern GPUs have up to 2048 shaders...
Thanks! 
So, refactoring...Code:
Assuming a worst case scenario, with each wavefront composed of 2048 threads with 4 vectors each:
lambda = 1/(2^32)*2048*4
Poisson(k) = (lambda^k)*(exp^(-lambda))/(k!)
Probability of finding 1 nonce in a wavefront:
P = Poisson(1) = 1.9073e-06
P = Binomial(1, 8192, 1/(2^32)) = 1.9073e-06
Probability of finding 2 nonces in a wavefront:
P = Poisson(2) = 1.8190e-12
P = Binomial(2, 8192, 1/(2^32)) = 1.8188e-12
So, if they all end at the same time (or during the non-atomic mem write op), for every ~1.000.000 found nonces you'll throw one away (overwritten). If using vectors 2, every 2.1e6, and vectors 1 every 4.2e6.
On a 1GH/s card, where finding a nonce takes about ~4.3s, it will take around 50 days of 24/7 runtime for the vectors 4 case to happen once.
October 15, 2012, 05:55:36 PM
Yes but that would make my 2.722 Gh only appear as 2.7GH which is not accurate enough. Significant digits is the key.
October 15, 2012, 05:52:47 PM
Just updated to 2.8.3. I have to say I really don't like the new precision on numeric output:
Could you put a .0 on there instead of all that blank space? It's a minor thing, but I like it better that way.
This is a side effect of trying to find a generic format that is aligned on the screen and fits values from 0 to 18,446,744,073,709,551,616 in a generic way, while still maintaining adequate precision for the relative rate for that device. It is not entirely straight forward and what to do about zeroes is not ever going to be to everyone's satisfaction. 001.0 or 01.00 or 1.000 ? Quote
GPU 0: 73.0C 2900RPM | 604.2M/661.2Mh/s | A:3 R:0 HW:0 U: 7.03/m I: 9
GPU 1: 74.0C 2912RPM | 595.1M/659.3Mh/s | A:5 R:0 HW:0 U:11.72/m I: 9
GPU 2: 74.0C 2922RPM | 611.8M/658 Mh/s | A:10 R:0 HW:0 U:23.44/m I: 9
GPU 1: 74.0C 2912RPM | 595.1M/659.3Mh/s | A:5 R:0 HW:0 U:11.72/m I: 9
GPU 2: 74.0C 2922RPM | 611.8M/658 Mh/s | A:10 R:0 HW:0 U:23.44/m I: 9
Could you put a .0 on there instead of all that blank space? It's a minor thing, but I like it better that way.
By the way, that massive value would show up as 18.45EH/s with that current scheme, so that it could show up aligned on the same screen as something with 0.001 H/s.
Thanks - I figured as much. The units allow you to have a maximum 3 digits on the left side, though, so you could simply lay it out such that there is a space-padded 3-digit integer part and a 1 digit decimal part all the time, no matter what, meaning:
Quote
604.2M/661.2Mh/s
595.1M/659.3Mh/s
611.8M/658.0Mh/s
595.1M/659.3Mh/s
611.8M/658.0Mh/s
In my case, and using your example:
Quote
604.2M/661.2Mh/s
595.1M/659.3Mh/s
611.8M/658.0Mh/s
18.5E/ 18.5Eh/s
595.1M/659.3Mh/s
611.8M/658.0Mh/s
18.5E/ 18.5Eh/s
October 15, 2012, 05:35:47 PM
I've noticed that the GPU core temp is no longer being displayed on the output from version 2.8.3 for my 5850 on Win7x64. Previously when using 2.7.6 and before it was outputing GPU temps. No change in SDK/Driver, the only change was the cgminer.exe binary. I looked over the config, and nothing looks too different -
What am I missing in order to output/log GPU temps?
Log file from cgminer 2.8.3
Log file from cgminer 2.7.6
What am I missing in order to output/log GPU temps?
Quote from: My_Startup_script
>>"%LOGFILEANDPATH%" 2>&1 cgminer.exe -T --kernel-path "%PATHTOKERNELS%" --kernel phatk --device 0 --verbose --log 30 --gpu-vddc 1.088 --gpu-engine 977 --gpu-memclock 300 --intensity 10 --queue 8 --gpu-threads 4 --worksize 256 %POOLSSTRING%
Log file from cgminer 2.8.3
Code:
[2012-10-15 17:04:35] Started cgminer 2.8.3
[2012-10-15 17:04:36] CL Platform 0 vendor: Advanced Micro Devices, Inc.
[2012-10-15 17:04:36] CL Platform 0 name: AMD Accelerated Parallel Processing
[2012-10-15 17:04:36] CL Platform 0 version: OpenCL 1.1 AMD-APP-SDK-v2.5 (732.1)
[2012-10-15 17:04:36] Platform 0 devices: 1
[2012-10-15 17:04:36] 0 Cypress
[2012-10-15 17:04:36] Failed to ADL_Adapter_ID_Get. Error -1
[2012-10-15 17:04:36] Failed to ADL_Adapter_ID_Get. Error -1
[2012-10-15 17:04:36] GPU 0 ATI Radeon HD 5800 Series hardware monitoring enabled
[2012-10-15 17:04:36] Setting GPU 0 engine clock to 977
[2012-10-15 17:04:36] Setting GPU 0 memory clock to 300
[2012-10-15 17:04:36] Setting GPU 0 voltage to 1.088
[2012-10-15 17:04:36] Probing for an alive pool
[2012-10-15 17:04:36] Testing pool http://localhost:9332
[2012-10-15 17:04:36] HTTP request failed: Empty reply from server
[2012-10-15 17:04:36] Stratum authorisation success for pool 0
[2012-10-15 17:04:36] Pool 0 http://localhost:9332 active
[2012-10-15 17:04:36] Init GPU thread 0 GPU 0 virtual GPU 0
[2012-10-15 17:04:36] CL Platform vendor: Advanced Micro Devices, Inc.
[2012-10-15 17:04:36] CL Platform name: AMD Accelerated Parallel Processing
[2012-10-15 17:04:36] CL Platform version: OpenCL 1.1 AMD-APP-SDK-v2.5 (732.1)
[2012-10-15 17:04:36] List of devices:
[2012-10-15 17:04:36] 0 Cypress
[2012-10-15 17:04:36] Selected 0: Cypress
[2012-10-15 17:04:36] Initialising kernel phatk120823.cl with bitalign, 2 vectors and worksize 256
[2012-10-15 17:04:36] initCl() finished. Found Cypress
[2012-10-15 17:04:36] Init GPU thread 1 GPU 0 virtual GPU 0
[2012-10-15 17:04:36] CL Platform vendor: Advanced Micro Devices, Inc.
[2012-10-15 17:04:36] CL Platform name: AMD Accelerated Parallel Processing
[2012-10-15 17:04:36] CL Platform version: OpenCL 1.1 AMD-APP-SDK-v2.5 (732.1)
[2012-10-15 17:04:36] List of devices:
[2012-10-15 17:04:36] 0 Cypress
[2012-10-15 17:04:36] Selected 0: Cypress
[2012-10-15 17:04:37] Initialising kernel phatk120823.cl with bitalign, 2 vectors and worksize 256
[2012-10-15 17:04:37] initCl() finished. Found Cypress
[2012-10-15 17:04:37] Init GPU thread 2 GPU 0 virtual GPU 0
[2012-10-15 17:04:37] CL Platform vendor: Advanced Micro Devices, Inc.
[2012-10-15 17:04:37] CL Platform name: AMD Accelerated Parallel Processing
[2012-10-15 17:04:37] CL Platform version: OpenCL 1.1 AMD-APP-SDK-v2.5 (732.1)
[2012-10-15 17:04:37] List of devices:
[2012-10-15 17:04:37] 0 Cypress
[2012-10-15 17:04:37] Selected 0: Cypress
[2012-10-15 17:04:37] Initialising kernel phatk120823.cl with bitalign, 2 vectors and worksize 256
[2012-10-15 17:04:37] initCl() finished. Found Cypress
[2012-10-15 17:04:37] Init GPU thread 3 GPU 0 virtual GPU 0
[2012-10-15 17:04:37] CL Platform vendor: Advanced Micro Devices, Inc.
[2012-10-15 17:04:37] CL Platform name: AMD Accelerated Parallel Processing
[2012-10-15 17:04:37] CL Platform version: OpenCL 1.1 AMD-APP-SDK-v2.5 (732.1)
[2012-10-15 17:04:37] List of devices:
[2012-10-15 17:04:37] 0 Cypress
[2012-10-1 [2012-10-15 17:04:38] Submitting share d72f00f1 to pool 0
[2012-10-15 17:04:39] Accepted d72f00f1 Diff 1/1 GPU 0 pool 0
[2012-10-15 17:04:39] New block: 0000039f47f7ac4bdb5b4c64abb1a9c3...
[2012-10-15 17:04:39] Stratum from pool 0 detected new block
[2012-10-15 17:04:39] Initialising kernel phatk120823.cl with bitalign, 2 vectors and worksize 256
[2012-10-15 17:04:39] initCl() finished. Found Cypress
[2012-10-15 17:04:39] 4 gpu miner threads started
...
(30s):416.7M (avg):406.7Mh/s | Q:2803 A:7542 R:21 HW:0 E:269% U:5.6/m
...
(30s):437.4M (avg):406.7Mh/s | Q:2810 A:7572 R:21 HW:0 E:269% U:5.6/m
...
(30s):397.1M (avg):406.7Mh/s | Q:2811 A:7575 R:21 HW:0 E:269% U:5.6/m
...
(30s):396.2M (avg):406.7Mh/s | Q:2812 A:7580 R:21 HW:0 E:270% U:5.6/m
..
Log file from cgminer 2.7.6
Code:
[2012-09-27 16:08:00] Started cgminer 2.7.6
[2012-09-27 16:08:00] CL Platform 0 vendor: Advanced Micro Devices, Inc.
[2012-09-27 16:08:00] CL Platform 0 name: AMD Accelerated Parallel Processing
[2012-09-27 16:08:00] CL Platform 0 version: OpenCL 1.1 AMD-APP-SDK-v2.5 (732.1)
[2012-09-27 16:08:00] Platform 0 devices: 1
[2012-09-27 16:08:00] 0 Cypress
[2012-09-27 16:08:01] Failed to ADL_Adapter_ID_Get. Error -1
[2012-09-27 16:08:01] Failed to ADL_Adapter_ID_Get. Error -1
[2012-09-27 16:08:01] GPU 0 ATI Radeon HD 5800 Series hardware monitoring enabled
[2012-09-27 16:08:01] Setting GPU 0 engine clock to 980
[2012-09-27 16:08:01] Setting GPU 0 memory clock to 300
[2012-09-27 16:08:01] Setting GPU 0 voltage to 1.088
[2012-09-27 16:08:01] Probing for an alive pool
[2012-09-27 16:08:01] Testing pool http://localhost:8336
[2012-09-27 16:08:01] Pool 0 http://localhost:8336 active
[2012-09-27 16:08:01] Init GPU thread 0 GPU 0 virtual GPU 0
[2012-09-27 16:08:01] CL Platform vendor: Advanced Micro Devices, Inc.
[2012-09-27 16:08:01] Long-polling activated for http://localhost:8336/lp
[2012-09-27 16:08:01] CL Platform name: AMD Accelerated Parallel Processing
[2012-09-27 16:08:01] CL Platform version: OpenCL 1.1 AMD-APP-SDK-v2.5 (732.1)
[2012-09-27 16:08:01] List of devices:
[2012-09-27 16:08:01] 0 Cypress
[2012-09-27 16:08:01] New block: 0000051dcdc2f44fd0bfc7859eb9921a...
[2012-09-27 16:08:01] Selected 0: Cypress
[2012-09-27 16:08:01] Initialising kernel phatk120823.cl with bitalign, 2 vectors and worksize 256
[2012-09-27 16:08:01] initCl() finished. Found Cypress
[2012-09-27 16:08:01] Init GPU thread 1 GPU 0 virtual GPU 0
[2012-09-27 16:08:01] CL Platform vendor: Advanced Micro Devices, Inc.
[2012-09-27 16:08:01] CL Platform name: AMD Accelerated Parallel Processing
[2012-09-27 16:08:01] CL Platform version: OpenCL 1.1 AMD-APP-SDK-v2.5 (732.1)
[2012-09-27 16:08:01] List of devices:
[2012-09-27 16:08:01] 0 Cypress
[2012-09-27 16:08:01] Selected 0: Cypress
[2012-09-27 16:08:01] Pool 0 http://localhost:8336 alive
[2012-09-27 16:08:02] Initialising kernel phatk120823.cl with bitalign, 2 vectors and worksize 256
[2012-09-27 16:08:02] initCl() finished. Found Cypress
[2012-09-27 16:08:02] Init GPU thread 2 GPU 0 virtual GPU 0
[2012-09-27 16:08:02] CL Platform vendor: Advanced Micro Devices, Inc.
[2012-09-27 16:08:02] CL Platform name: AMD Accelerated Parallel Processing
[2012-09-27 16:08:02] CL Platform version: OpenCL 1.1 AMD-APP-SDK-v2.5 (732.1)
[2012-09-27 16:08:02] List of devices:
[2012-09-27 16:08:02] 0 Cypress
[2012-09-27 16:08:02] Selected 0: Cypress
[2012-09-27 16:08:02] Initialising kernel phatk120823.cl with bitalign, 2 vectors and worksize 256
[2012-09-27 16:08:03] initCl() finished. Found Cypress
[2012-09-27 16:08:03] Init GPU thread 3 GPU 0 virtual GPU 0
[2012-09-27 16:08:03] CL Platform vendor: Advanced Micro Devices, Inc.
[2012-09-27 16:08:03] CL Platform name: AMD Accelerated Parallel Processing
[2012-09-27 16:08:03] CL Platform version: OpenCL 1.1 AMD-APP-SDK-v2.5 (732.1)
[2012-09-27 16:08:03] List of dev [2012-09-27 16:08:03] 0 Cypress
[2012-09-27 16:08:03] Selected 0: Cypress
[2012-09-27 16:08:04] Initialising kernel phatk120823.cl with bitalign, 2 vectors and worksize 256
[2012-09-27 16:08:04] initCl() finished. Found Cypress
[2012-09-27 16:08:04] 4 gpu miner threads started
...
...
[2012-09-27 17:45:18] Accepted 21adfc25 Diff 1 GPU 0 pool 0
[2012-09-27 17:45:18] GPU0 67.0C 3237RPM | (30s):408.2 (avg):407.7 Mh/s | A:562 R:3 HW:0 U:5.8/m I:10
[2012-09-27 17:45:20] Accepted 729a0594 Diff 1 GPU 0 pool 0
[2012-09-27 17:45:20] GPU0 67.0C 3250RPM | (30s):408.2 (avg):407.7 Mh/s | A:563 R:3 HW:0 U:5.8/m I:10
[2012-09-27 17:45:34] Accepted 0a38cdc3 Diff 1 GPU 0 pool 0
[2012-09-27 17:45:34] GPU0 67.0C 3227RPM | (30s):409.1 (avg):408.9 Mh/s | A:564 R:3 HW:0 U:5.8/m I:10
[2012-09-27 17:45:40] Accepted 8b296886 Diff 1 GPU 0 pool 0
[2012-09-27 17:45:40] GPU0 67.0C 3258RPM | (30s):408.7 (avg):409.4 Mh/s | A:565 R:3 HW:0 U:5.8/m I:10
October 15, 2012, 05:34:38 PM
Don't forget modern GPUs have up to 2048 shaders...
October 15, 2012, 05:27:14 PM
This is what I don't understand too well (sorry to bother you).
Let's assume, as you wrote, that your device has 1GH/s of computing power.
So what T do you like to choose?
If you choose T=1 sec, then the probabilty to find one nonce in T is the mean, so is lambda. Lambda is 1/4.3=0.23. 23%.
The probability to find two nonces in T, according to Poisson distribution, is ((0.2325^2)*e^-0.2325)/2!=0.021. 2,1%.
Depends on what question you are trying to solve. The question you answered above is "What is the probability of finding k nonces in a period of 1s? And in a period of 2s?"Let's assume, as you wrote, that your device has 1GH/s of computing power.
So what T do you like to choose?
If you choose T=1 sec, then the probabilty to find one nonce in T is the mean, so is lambda. Lambda is 1/4.3=0.23. 23%.
The probability to find two nonces in T, according to Poisson distribution, is ((0.2325^2)*e^-0.2325)/2!=0.021. 2,1%.
That was not the question I was answering. My question was "What is the probability of finding k nonces at the same time?"
If you choose T=1/1E9 sec, AKA the clock tick duration of your device, then I calculate the probability to simultaneously find two or more nonces this way:
a) if your device processes hashes sequentially (one thread), of course there cannot be simultaneous nonces if we consider T=1/1E9 sec =1/(GPU hashes per timeframe);
b) if your device processes more than one hash simultaneously (more threads), there can be simultaneous nonces, but every thread uses just a part of the device computing power. Let's say we have five threads. Each thread is capable of 200MH/s, so it finds a nonce in about 21.47 sec (that is: 2^32 H / 200MH/s). In 1/1E9 sec each thread finds a mean of 1/21.47G nonces.
The problem is independent of thread execution time, because that is relatively constant. They all end at mostly the same time in a wavefront. The problem is: when they all end, how many have nonces? a) if your device processes hashes sequentially (one thread), of course there cannot be simultaneous nonces if we consider T=1/1E9 sec =1/(GPU hashes per timeframe);
b) if your device processes more than one hash simultaneously (more threads), there can be simultaneous nonces, but every thread uses just a part of the device computing power. Let's say we have five threads. Each thread is capable of 200MH/s, so it finds a nonce in about 21.47 sec (that is: 2^32 H / 200MH/s). In 1/1E9 sec each thread finds a mean of 1/21.47G nonces.
The probability that at least N of our five threads find a nonce in the same clock is 1/21.47G^N. We can say zero, and we don't need any Poisson distribution for it.
When n->inf and p->0 the Poisson follows the Binomial, so either gives the same results: https://en.wikipedia.org/wiki/Poisson_limit_theoremI can rewrite everything in another way, using another example:
Code:
Assuming each wavefront composed of 256 threads with 2 vectors each:
lambda = 1/(2^32)*256*2
Poisson(k) = (lambda^k)*(exp^(-lambda))/(k!)
Probability of finding 1 nounce in a wavefront:
P = Poisson(1) = 1.1921e-07
P = Binomial(1, 512, 1/(2^32)) = 1.1921e-07
Probability of finding 2 nounces in a wavefront:
P = Poisson(2) = 7.1054e-15
P = Binomial(2, 512, 1/(2^32)) = 7.0915e-15
October 15, 2012, 03:28:27 PM
I'm using 2.8.3 with Linux.
I mine on many pools, and I do hop on some of them, having the others as backups, so pool switches are common here.
My only stratum pool is Slush. I have it in my configuration file as: so I leave it to cgminer to recognize ad activate the stratum protocol, which it does:
But after a few hours that cgminer is running, I always find this stratum pool as "Enabled Dead".
While mining on another pool, in the log I see things like:
but, checking immediately after that, in the Pools section the pool is showed as "Enabled Dead", and it will remain dead forever. As soon as I restart cgminer, the pool is alive again (so it's not a pool problem).
I don't know if it happens every time the pool doesn't respond for a while, or whenever my box changes its IP address. I'm just sure it happens at least every few hours.
HTH.
I noticed this also when I used BTC Guild as a backup for a while. I just assumed they were sick of me using them for detecting new blocks sooner without actually giving much work back; I had just as many getworks with them as I did with my primary pool. I mine on many pools, and I do hop on some of them, having the others as backups, so pool switches are common here.
My only stratum pool is Slush. I have it in my configuration file as:
Code:
"url" : "http://api.bitcoin.cz:8332"
Code:
Switching pool 7 http://api.bitcoin.cz:8332 to stratum+tcp://api-stratum.bitcoin.cz:3333
While mining on another pool, in the log I see things like:
Code:
[2012-10-15 01:31:50] Pool 7 http://api.bitcoin.cz:8332 not responding!
[2012-10-15 01:31:51] Pool 7 http://api.bitcoin.cz:8332 alive
I don't know if it happens every time the pool doesn't respond for a while, or whenever my box changes its IP address. I'm just sure it happens at least every few hours.
HTH.
I haven't seen this myself but there could well still be a bug in there. I'll keep auditing code.
October 15, 2012, 03:26:34 PM
Do you have higher difficulty?
If you use stratum protocol and your workers give too much hashes, the pool increases difficulty for you, so you have less shares but get paid better per share.
CGM shows that in the shares line.
If you use stratum protocol and your workers give too much hashes, the pool increases difficulty for you, so you have less shares but get paid better per share.
CGM shows that in the shares line.
October 15, 2012, 03:11:18 PM
I used the new 2.8.3 and its noticeably slower for some reason. My Mhash is the same as 2.7.5 but the the accepts shares are like significantly less. I usually do about 600 shares an hour with this im doing 120 shares
October 15, 2012, 12:31:14 PM
My above Poisson math is for the case of 2 simultaneous nonce finds (that's why lambda=1/(2^32) and not lambda=1/(2^32)*1E9).
This is what I don't understand too well (sorry to bother you).
Let's assume, as you wrote, that your device has 1GH/s of computing power.
So what T do you like to choose?
If you choose T=1 sec, then the probabilty to find one nonce in T is the mean, so is lambda. Lambda is 1/4.3=0.23. 23%.
The probability to find two nonces in T, according to Poisson distribution, is ((0.2325^2)*e^-0.2325)/2!=0.021. 2,1%.
If you choose T=1/1E9 sec, AKA the clock tick duration of your device, then I calculate the probability to simultaneously find two or more nonces this way:
a) if your device processes hashes sequentially (one thread), of course there cannot be simultaneous nonces if we consider
T=1/1E9 sec =1/(GPU hashes per timeframe);
b) if your device processes more than one hash simultaneously (more threads), there can be simultaneous nonces, but every thread uses just a part of the device computing power. Let's say we have five threads. Each thread is capable of 200MH/s, so it finds a nonce in about 21.47 sec (that is: 2^32 H / 200MH/s)
In 1/1E9 sec each thread finds a mean of 1/21.47G nonces.
The probability that at least N of our five threads find a nonce in the same clock is 1/21.47G^N. We can say zero, and we don't need any Poisson distribution for it.
October 15, 2012, 10:48:01 AM
Sorry, I haven't followed your whole discussion, but as soon as I read this message it looked to me a bit weird.
I apologize in advance if I have misread or misunderstood something.
In Poisson distribution, the period of time taken into account is fixed. Let's call it T.
Lambda is the mean of Poisson distribution (and its variance too). So with lambda=1/2^32 you're stating that you expect to find 1/2^32 nonces in T. That is: you expect to wait (2^32) Ts to find a single nonce.
R U sure?
And what do you mean with:
I apologize in advance if I have misread or misunderstood something.
In Poisson distribution, the period of time taken into account is fixed. Let's call it T.
Lambda is the mean of Poisson distribution (and its variance too). So with lambda=1/2^32 you're stating that you expect to find 1/2^32 nonces in T. That is: you expect to wait (2^32) Ts to find a single nonce.
R U sure?
And what do you mean with:
Quote
Poisson(2)*1E9
Besides, your calculation looks wrong. With lambda=1/2^32, P(2) is ... almost zero. P(2)*1E9 isn't much more, and we can round it to zero as well. That's correct, you are expecting to find 1 nonce out of 2^32 cases in T=1/(GPU hashes per timeframe). On the example above, T=1/(1E9).
Each processed 32-bit hash has a probability of 1/(2^32) of being a nonce. So a card that processes 1.000.000 hashes/s has a probability of finding one each (2^32)/1E9 = 4.3 seconds.
My above Poisson math is for the case of 2 simultaneous nonce finds (that's why lambda=1/(2^32) and not lambda=1/(2^32)*1E9).
October 15, 2012, 09:52:16 AM
Still, the odds for concurrency are very very low.
A nonce find can be modeled by a Poisson distribution with lambda=1/(2^32).
A nonce find can be modeled by a Poisson distribution with lambda=1/(2^32).
Code:
Taking the example of a 1GHS card (sum of all wavefronts speed/second):
lambda = 1/(2^32)
Poisson(k) = (lambda^k)*(exp^(-lambda))/(k!)
Probability of finding 2 nounces (at the same time) per second:
P = Poisson(2)*1E9 = 2.7105e-11 = ~.0000000027%
Sorry, I haven't followed your whole discussion, but as soon as I read this message it looked to me a bit weird.
I apologize in advance if I have misread or misunderstood something.
In Poisson distribution, the period of time taken into account is fixed. Let's call it T.
Lambda is the mean of Poisson distribution (and its variance too). So with lambda=1/2^32 you're stating that you expect to find 1/2^32 nonces in T. That is: you expect to wait (2^32) Ts to find a single nonce.
R U sure?
And what do you mean with:
Quote
Poisson(2)*1E9
Besides, your calculation looks wrong. With lambda=1/2^32, P(2) is ... almost zero. P(2)*1E9 isn't much more, and we can round it to zero as well. Jump to: