How to activate hyperthreading on wrfems

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Giancarlo Modugno
Posts: 59
Joined: Tue Jun 05, 2012 5:25 pm

How to activate hyperthreading on wrfems

Post by Giancarlo Modugno » Wed Jun 17, 2015 8:00 am

Hi,

how can I activate hyperthreading on my wrfems? My server admin assures me that it is just activate on the ubuntu server that I use.

Thank you

meteoadriatic
Posts: 1510
Joined: Wed Aug 19, 2009 10:05 am

Re: How to activate hyperthreading on wrfems

Post by meteoadriatic » Wed Jun 17, 2015 8:16 am

Hello,

see with

Code: Select all

cat /proc/cpuinfo
how many CPU threads you have. That should give you answer if HT is enabled or not. If it is you will have double threads than real CPU cores. If not, it will be same.

Giancarlo Modugno
Posts: 59
Joined: Tue Jun 05, 2012 5:25 pm

Re: How to activate hyperthreading on wrfems

Post by Giancarlo Modugno » Wed Jun 17, 2015 8:21 am

that's the last :
processor : 23
vendor_id : GenuineIntel
cpu family : 6
model : 44
model name : Intel(R) Xeon(R) CPU X5650 @ 2.67GHz
stepping : 2
microcode : 0x14
cpu MHz : 2668.000
cache size : 12288 KB
physical id : 1
siblings : 12
core id : 10
cpu cores : 6
apicid : 53
initial apicid : 53
fpu : yes
fpu_exception : yes
cpuid level : 11
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 popcnt lahf_lm ida arat epb dtherm tpr_shadow vnmi flexpriority ept vpid
bogomips : 5333.55
clflush size : 64
cache_alignment : 64
address sizes : 40 bits physical, 48 bits virtual
power management:

meteoadriatic
Posts: 1510
Joined: Wed Aug 19, 2009 10:05 am

Re: How to activate hyperthreading on wrfems

Post by meteoadriatic » Wed Jun 17, 2015 8:33 am

OK so you have 24 "logical cores". And, I guess you have two Xeon X5650, each with 6 cores, that totals 12 physical cores, then yes, HT is enabled.

Run your WRF with something like 22 or 23 threads, that will probably give best speed. However, test and see which number of threads runs your domain fastest.

Giancarlo Modugno
Posts: 59
Joined: Tue Jun 05, 2012 5:25 pm

Re: How to activate hyperthreading on wrfems

Post by Giancarlo Modugno » Wed Jun 17, 2015 8:43 am

ok thank you.

What is the correct configuration variabile that I have to set and in which file?

meteoadriatic
Posts: 1510
Joined: Wed Aug 19, 2009 10:05 am

Re: How to activate hyperthreading on wrfems

Post by meteoadriatic » Wed Jun 17, 2015 9:00 am

wrfems/runs/<domain>/conf/ems_run/run_ncpus.conf

REAL_NODECPUS = local:N
WRFM_NODECPUS = local:N

Set those N to 22 or 23. But, having a bug in real in a sense that it does not do proper job with lot of threads, use something like 4, not more on REAL_NODECPUS. For WRFM_NODECPUS go on and test what gives maximum speed (I guess 22 or 23).

Also:
http://strc.comet.ucar.edu/software/new ... pter08.pdf

Giancarlo Modugno
Posts: 59
Joined: Tue Jun 05, 2012 5:25 pm

Re: How to activate hyperthreading on wrfems

Post by Giancarlo Modugno » Mon Jun 29, 2015 2:01 pm

Thank you very much.

Now, I now that a server with no-other processes is better BUT I have just done a try with other processes ...

Results for 6hours of simulation:

processor - seconds

12 - 144
13 - 135
14 - 127

15 - 149
16 - 156
17 - 159
18 - 148
19 - 171
20 - 168
21 - 157
22 - 162

then, another simulation with 14 core in 126 seconds after 22 core; I has thought that too much time was for busy cpu but... the third simulation with 14 core in 131 seconds (above the 13 core simulation). Now I think that my minimum simulation time is with 14 core.

My answer is: there is a mimum / maximum core number for every different domain?

norulz
Posts: 68
Joined: Thu Mar 12, 2015 1:43 pm

Re: How to activate hyperthreading on wrfems

Post by norulz » Tue Jun 30, 2015 9:27 am

Hi,

Interesting!

Did you benchmark the same domain without hyperthreading?
i.e with 11 cpus?


David

Giancarlo Modugno
Posts: 59
Joined: Tue Jun 05, 2012 5:25 pm

Re: How to activate hyperthreading on wrfems

Post by Giancarlo Modugno » Wed Jul 01, 2015 3:42 pm

Hi norulz,

yes but with another domain, thus double experiment: different (larger) domain + no / yes HT (from 8 to 23 cores)

RESULT: I have found a minimum simulation time using, nother time, 14 processor and a similar behaviour from 12 to 23 cores with the last experiment.

Now, I'm starting to think that it could be a rule for my server...!

bye

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