Thanks for the tips! Unfortunately, I am not seeing anything in /var/log of interest. The mcelog service is not enabled. I do not see anything /proc/interrupts either.

I will look into full power down , memtester and firmare update. It is a blade. We do not have Intel cluster checker, but we have DRAC ( Dell Remote Access Controller ). I just logged in there and everything checks out, i.e memory, power etc.



Quoting John Hearns via Beowulf <beowulf@beowulf.org>:

Another thing to perhaps look at. Are you seeing messages abotu thermal
throttling events in the system logs?
Could that node have a piece of debris caught in its air intake?

I dont think that will produce a 30% drop in perfoemance. But I have caught
compute nodes with pieces of packaking sucked onto the front,
following careless peeople unpacking kit in machine rooms.
(Firm rule - no packaging in the machine room. This means you)




On 10 August 2017 at 17:00, John Hearns <hear...@googlemail.com> wrote:

ps.   Look at   watch  cat /proc/interrupts   also
You might get a qualitative idea of a huge rate of interrupts.


On 10 August 2017 at 16:59, John Hearns <hear...@googlemail.com> wrote:

Faraz,
   I think you might have to buy me a virtual coffee. Or a beer!
Please look at the hardware health of that machine. Specifically the
DIMMS.  I have seen this before!
If you have some DIMMS which are faulty and are generating ECC errors,
then if the mcelog service is enabled
an interrupt is generated for every ECC event. SO the system is spending
time servicing these interrupts.

So:   look in your /var/log/mcelog for hardware errors
Look in your /var/log/messages for hardware errors also
Look in the IPMI event logs for ECC errors:    ipmitool sel elist

I would also bring that node down and boot it with memtester.
If there is a DIMM which is that badly faulty then memtester will
discover it within minutes.

Or it could be something else - in which case I get no coffee.

Also Intel cluster checker is intended to exacly deal with these
situations.
What is your cluster manager, and is Intel CLuster Checker available to
you?
I would seriously look at getting this installed.







On 10 August 2017 at 16:39, Faraz Hussain <i...@feacluster.com> wrote:

One of our compute nodes runs ~30% slower than others. It has the exact
same image so I am baffled why it is running slow . I have tested OMP and
MPI benchmarks. Everything runs slower. The cpu usage goes to 2000%, so all
looks normal there.

I thought it may have to do with cpu scaling, i.e when the kernel
changes the cpu speed depending on the workload. But we do not have that
enabled on these machines.

Here is a snippet from "cat /proc/cpuinfo". Everything is identical to
our other nodes. Any suggestions on what else to check? I have tried
rebooting it.

processor       : 19
vendor_id       : GenuineIntel
cpu family      : 6
model           : 62
model name      : Intel(R) Xeon(R) CPU E5-2670 v2 @ 2.50GHz
stepping        : 4
cpu MHz         : 2500.098
cache size      : 25600 KB
physical id     : 1
siblings        : 10
core id         : 12
cpu cores       : 10
apicid          : 56
initial apicid  : 56
fpu             : yes
fpu_exception   : yes
cpuid level     : 13
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 xtopology
nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2
ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt
tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm ida arat xsaveopt pln
pts dts tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms
bogomips        : 5004.97
clflush size    : 64
cache_alignment : 64
address sizes   : 46 bits physical, 48 bits virtual
power management:



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