LTC mining with Reaper on a 7970

[exahash]

Anyone else tried this?  What are your litecoin.conf settings?  Especially if you have a 7970.  I'm under Win7 using the newest 64-bit reaper from the wiki. http://wiki.solidcoin.info/wiki/Reaper

I'm getting about 236 kh/s at stock clocks and voltage, and Afterburner shows the GPU at 96% usage with the following settings in litecoin.conf:

worksize 256
aggression 12
threads_per_gpu 4
sharethreads 18
lookup_gap 2
gpu_thread_concurrency 6144

If I increase the aggression above 12 I get lots of stales/invalids and the message "Weird response from server"

I'm wondering what the last three settings do (sharethreads, lookup_gap, gpu_thread_concurrency).  I noticed that gpu_thread_concurrency is 3x my 2048 stream processors and tried other multiples of 2048 but that didn't help.  I also tried different values for lookup_gap but none were any better.

If I reduce threads_per_gpu below 3, performance drops into the high 220's and gpu usage in afterburner drops to low 90's

I'd also like to know how this is performing on 5850's and 5970's, since I have a bunch more of those.

[1714907671]

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[Ahimoth]

I think I can answer the gpu_thread_concurrency number. This should be set to [shaders per gpu] multiplied by the [shader "threads" supported].

Examples:
A 6950 has 1408 shaders, and each shader can queue 4 threads, so the optimal number for this card is 5632.
A 6990 has 1536 shaders, and each shader can queue 4 threads, so the optimal number for this card is 6144.

I think the 5xxx cards were 5 threads queued per shader, so there it would be 5 times the shader count.

I do not know how many "threads" each shader on a 7 series can queue.

[Tittiez]

Funny, I get higher kH/s on my 6850 with 6144 then I do its optimal number (3840).

[Ahimoth]

Well, that's just what I've been told. And I only have 6950's to test on.

However, that said I believe 6850 is VLIW5, so might want to try 5 x 960 = 4800

[Rubberduckie]

Am I right in thinking a 6870 has 1120 shaders,4 threads so 4480?

[Ahimoth]

All 68xx series cards are still vliw5 to my knowledge, which I think means they have a queue of 5 threads per shader. So a 6870 would be 5 * 1120 = 5600

[Tittiez]

Am I right in thinking a 6870 has 1120 shaders,4 threads so 4480?

Yeah, the 6850 has 960 shaders according to AMDs site.

So 960 * 5 = 4800
I get exactly 250kh/s at aggression 17.

With it at 6144 I get 259kh/s with aggression 17 and 250kh/s with aggression 16.

[ShadowAlexey]

You might be missing fact that it has 68**/58** series has simd wich perform 5 operation,thats how we get 1120/1600,of the actual count of processors is 224 for 6870 and 320 for 5870, so i cant find any connection to gpu_thread_concurrency...
According to OpenCL File this is size of x,the amount of main threads which would be the amount of threads we run i think...

[Rubberduckie]

All 68xx series cards are still vliw5 to my knowledge, which I think means they have a queue of 5 threads per shader. So a 6870 would be 5 * 1120 = 5600

just saw your post thx!

(stopped mining LTC for a day or so)

[Aseras]

Drop threads per gpu to one overclocking the memory. Litecoin is dependent on high memory speed unlike bitcoin.

[Aseras]

right. play with it and see what happens.  The highest you can get the memory the better. the core helps too, but memory speed is more important.

on a 6990 having the ram at 800mhz vs 1250mhz is the difference between 200khash and 800khash

[Aseras]

right. play with it and see what happens.  The highest you can get the memory the better. the core helps too, but memory speed is more important.

on a 6990 having the ram at 800mhz vs 1250mhz is the difference between 200khash and 800khash

Duh play with it. There are just a lot of options to mess with compared to btc mining and very little info I can find. Thanks

ok delete the bin files between runs.

worksize try 128 or 256 mine for a couple of minutes and see what gets the best rate.

aggression 12-19

Lower if you want to use the box for anything and background mine or if stales are too high. Higher for dedicated. beyond 19 isnt good.

threads per gpu, try them all 1, 2 and 4.  mine for a couple of minutes and see what gets the best rate.

sharethreads, lookupgap leave alone.



concurrency, start at 8192 and go up. try multiples of 1024 and again mine for a couple of minutes and see what gets the best rate

in half an hour you'll answer your own question.

[Aseras]

I have 2 7970 on order I'll tell you next week.

All I have right now are 5970 and 6990

for those


worksize 256
aggression 16
threads_per_gpu 1
sharethreads 18
lookup_gap 2
gpu_thread_concurrency 8192

works best

and again FAST memory, unlike bitcoin.

[tacotime]

these settings get 600kh/s+, which is the estimated kh/s rate for one of these cards by their memory bandwidth:

worksize 256
aggression 13
threads_per_gpu 5
sharethreads 18
lookup_gap 2
gpu_thread_concurrency 10240

you need the latest sdk and 12.6+ ati drivers (tried with 12.6 and it works well, not sure about 12.7 but those are probably okay too)

[iCEBREAKER]

So I read through this thread, then looked at btc-e's LTC/BTC and LTC/$ pages.  But the coffee isn't working.

My head gets all spinny when I try to figure out whether to mine LTC on my 7970, or keep mining BTC and exchange them for LTC.

Can somebody please math this for me?

Has anyone made a LTC vs BTC profitability calculator?  I'll start a bounty for one. 

+1BTC

[pooler]

Has anyone made a LTC vs BTC profitability calculator?  I'll start a bounty for one. 

It already exists.
http://allchains.info/calc.html

[iCEBREAKER]

Has anyone made a LTC vs BTC profitability calculator?  I'll start a bounty for one. 

It already exists.
http://allchains.info/calc.html

Oh goody, thanks!!! 

[mig91]

i have allways 100% usage on cpu. how i can fix that? 

[goxed]

i have allways 100% usage on cpu. how i can fix that? 

Use latest cgminer 2.6.1  and run with --scrypt option

[mig91]

i have allways 100% usage on cpu. how i can fix that? 

Use latest cgminer 2.6.1  and run with --scrypt option

i fixed the cpu problem in reaper. i have 2x 6950 and im thinking which miner i should use? cgminer or reaper?

what is that "--scrypt option" in cgminer?

thanks for helping a noob