RANDOM-X on XEON... CACHE, FREQ'S OR CORES?

[MA3A]

INTEL S2600CW2SR with dual 2011 sockets that support Xeon V3 and V4 cpus.Trying to figure out what is the best watt/$ processor for this board to run XMRIG? Would CACHE be the first priority then NUMBER OF CORES and then FREQUENCY or how should i prioritize factors involved>?
Board supports up to 140W per socket.
Thanks

[joblo]

1. cache / cores

I believe RandomX use the same cache as the old Cryptonight, 2 MB/thread.
You only need as many cores as you have cache to support them.

2. Frequency

3. Cores, see 1.

[MA3A]

so for example E5 2670 V3 ( 12core 30mb 2,3ghz) vs E7 8893 (4core 45mb 3,2ghz)  
2670 should be better right?

[philipma1957]

so for example E5 2670 V3 ( 12core 30mb 2,3ghz) vs E7 8893 (4core 45mb 3,2ghz)  
2670 should be better right?

devide core into cache.

so   30/12 = 2.5   this works  since the 2.5 is bigger then 2 by just a bit


and

45/4 = 11.25   this works less since 11.25 is way bigger then   2


you can set threads used lower

if  you have say 40mb and 32 cores that is

40/32 = 1.25  this is under 2

so you would set this to

20 of the 32 cores


and get

40/20 = 2

get cheap cpu's with big cache

[joblo]

Adding some detail to phillipma's reply...

so for example E5 2670 V3 ( 12core 30mb 2,3ghz) vs E7 8893 (4core 45mb 3,2ghz)  
2670 should be better right?

devide core into cache.

so   30/12 = 2.5   this works  since the 2.5 is bigger then 2 by just a bit

joblo> this is a good match.

and

45/4 = 11.25   this works less since 11.25 is way bigger then   2

you can set threads used lower

if  you have say 40mb and 32 cores that is

40/32 = 1.25  this is under 2

so you would set this to

20 of the 32 cores

joblo> you have more cache than the  cores can use, need morecore with this much cache


and get

40/20 = 2

get cheap cpu's with big cache

A ratio of 2MB cache / core(thread) is optimum.

[antantti]

v3 and v4 Xeons are L2 limited on randomx no matter how much L3 they have.

2x 4627v3 ($100?) 20 threads @3GHz gives you 10k consuming 260w.

2x 2696v3 ($800?) 36 threads @2.8GHz gives you 18k consuming 290w.

To compare, L3 limited ryzen 3600 ($200) 12 threads @4.2GHz gives 7k consuming 100w.

[MA3A]

2x 2696v3 ($800?) 36 threads @2.8GHz gives you 18k consuming 290w

- this is a bit too much of $ in...

2x 4627v3 ($100?) 20 threads @3GHz gives you 10k consuming 260w

- this is very reasonable, where did you get numbers from?

i have found locally 2670 v3, will install soon and see what they are capable of

[antantti]

- this is very reasonable, where did you get numbers from?

i have found locally 2670 v3, will install soon and see what they are capable of

Had a chance to test many different v3 xeons and compare randomx performance to specs, some observations:

-algo needs 256Kb L2 for every thread so hyperthreading is basically useless, disable it to save power or use cpu affinity to bind threads to 'real' cores.
-turbo bins, models with highest all core turbo are the best.
-tdp, on higher core count models after optimal tweaking you start hitting the tdp wall and throttling starts, negative vcore offset helps to a point where cpu crashes due to too low voltage.
-xeons run really cool, with a decent cooler heat is never a problem.
-exploiting 'xeon v3 turbo hack' can boost mining performance easily 20-30%.

What I forgot to try was some REALLY tight memory timings like with ryzens, v3 supports only DDR4-2133 and depending on how many memory sticks you have it runs on 1-4 way mode.

For example, looking at 2670 v3 I see it is a 12c/24t cpu with tdp of 120w, 2.3GHz base clock and turbo 3/3/3/3/3/3/3/4/5/6/8/8 meaning it will run on 2.6-3.1 GHz depending on how many threads you are using. 12 threads @2.6GHz will end up somewhere in 5k range.

Most likely you are limited also on your INTEL S2600CW2SR motherboard and the lack of tuning options and/ or possibility to use cheap ES/QS processors.

Do a search for 'List_of_Intel_Haswell-based_Xeon_microprocessors', really nice listing which clearly shows the most important specs for mining.

[joblo]

Had a chance to test many different v3 xeons and compare randomx performance to specs, some observations:

Excellent info, very informative. I don't have any Xeons but it was still quite interesting.

Thanks for identifying the 256K L2 dependency, I wasn't previously aware of it.

With improvements to turbo boost, boosting more cores, the benefits of mining with
N/2 threads is increased.

[antantti]

Excellent info, very informative. I don't have any Xeons but it was still quite interesting.

Thanks for identifying the 256K L2 dependency, I wasn't previously aware of it.

To make matters worse latest xeons have more than enough of L2 but guess what... some L3 is missing.

To be on topic, XEON... CACHE, FREQ'S OR CORES?, perfect answer is FREQ x CORES without HT.

OT: Most cpu-algos are not L2 limited, must Do Your Own Research.

[MA3A]

-exploiting 'xeon v3 turbo hack' can boost mining performance easily 20-30%.

- never heard of this, can you point me?

I got my e5 2070 v3 installed. temps are good. I Get 5800hs out of both. Mem runs on two channels, bought more sticks, will get them next week installed, curious if 4 channels will do any good...
Comparing to two E5 2665 V2, the v3's are less powerful. I get 6200-6300Hs out of V2s

[antantti]

-exploiting 'xeon v3 turbo hack' can boost mining performance easily 20-30%.

- never heard of this, can you point me?

Looking at your signature, hehe...

Out for another year or so.

[Bitbtc8]

is Xeon X5650 or X5670 better for mining Monero compare to the latest Xeon CPUs in the market right now? any where I can see hashrate comparison?

[MA3A]

So added more ram, now its quad channel. no change in hash rate.
looks like this is it:
https://www.win-raid.com/t3874f16-GUIDE-Haswell-E-EP-Xeon-CPUID-F-Turbo-Unlock.html
http://www.miyconst.com/Blog/View/2081/xeon-e5-2600-v3-turbo-boost-unlock
http://www.xtremesystems.org/forums/showthread.php?293290-Various-Overclocker-discovers-Xeon-E5-V3-Errata-Engineers-exploit-to-unlock-Turbo

[joblo]

So added more ram, now its quad channel. no change in hash rate.

That caught my attention. I was thinking Ryzen was pushing 2 channel with too many threads
but apparently not.

The only algos I can think of that are memory bottlenecked are srcyptn2 and lyra2z330.

[DDante]

Intel Xeon CPUs are easier to configure for me than Ryzen, I still don't understand how Ryzen CPUs are made, one other thing is Xeon CPUs support AES, with AES you will definitely get higher hashrate compare to the default hashrate

[joblo]

Intel Xeon CPUs are easier to configure for me than Ryzen, I still don't understand how Ryzen CPUs are made, one other thing is Xeon CPUs support AES, with AES you will definitely get higher hashrate compare to the default hashrate

Every x86_64 CPU built in the last 10 years has AES.

I don't know what you mean that yoy don't unerstand how Ryzen's are made.
The only thing that affects mining is you need to set cpu affinity on Ryzen when using
fewer threads than avaiable. On Intel it isn't necessary.

On Intel thread 1 is on core 1 while on Ryzen thread 2 is on core 1 SMT with thread 0.
 
To use 8 of 16 threads on intel the default affinity 0x00ff assures only one thread per
physical core.
 
With Ryzen you need to specify affinity 0x5555 or 0xaaaa (alternating 0 & 1) to avoid putting 2
threads on the same physical core.

[tevador]

Every x86_64 CPU built in the last 10 years has AES.

Not true.

Counterexample: https://ark.intel.com/content/www/us/en/ark/products/87358/intel-pentium-processor-g3470-3m-cache-3-60-ghz.html

Released in Q1 2015.

[joblo]

Every x86_64 CPU built in the last 10 years has AES.

Not true.

Counterexample: https://ark.intel.com/content/www/us/en/ark/products/87358/intel-pentium-processor-g3470-3m-cache-3-60-ghz.html

Released in Q1 2015.

Your nick looks familiar.

You got me on a technicality, I don't consider Pemtium and Celeron true X86_64 specifically
because they are crippled implementations.

In practical terms I was correct but let me rephrase to be technically correct.

Every mainstream x86_64 CPU, excluding very low cost CPUs, like Pentiums and Celerons,
built in the last 10 years has AES.



 

[Wh@@@t]

is Xeon X5650 or X5670 better for mining Monero compare to the latest Xeon CPUs in the market right now? any where I can see hashrate comparison?

2*Xeon E5440 = 1200 H/s
2*Xeon X5670 = 3400 H/s
2*Xeon E5-2670 = 6700 H/s