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* DRAM power consumption with turbostat
@ 2022-01-30 10:27 Julia Lawall
  2022-02-06  8:29 ` Zhang Rui
  0 siblings, 1 reply; 4+ messages in thread
From: Julia Lawall @ 2022-01-30 10:27 UTC (permalink / raw)
  To: Len Brown; +Cc: linux-pm

Hello,

I was wondering whether the DRAM power consumption reported by turbostat
is reliable on recent Intel machines?

In particular, I observed that turbostat reported a high DRAM energy
comsumption on a machine (Intel 5128) with persistent memory, but where
the persistent memory was not being used.  A colleague did an experiemnt
on another machine with persistent memory, and reported:

-----

I didn't run the test on troll but on another server equipped with PM
where I was able to reproduce the bug and by reading directly the msr
registers, I see that:
CPU Energy units = 0.00006104J
DRAM Energy units = 0.00001526J

However turbostat assumes that the DRAM  Energy units is 0.00006104J when
it runs the computation to obtain Joules (hence the too-high value
returned by turbostat)

-----

I see the code in turbostat that just uses the CPU energy units value
(rapl_dram_energy_units_probe), but I don't know what was the MSR used to
collect the above information.  Overall, I am wondering if the DRAM energy
consumption values are reliable in cases with and without persistent
memory.

thanks,
julia

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2022-02-06  9:32 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2022-01-30 10:27 DRAM power consumption with turbostat Julia Lawall
2022-02-06  8:29 ` Zhang Rui
2022-02-06  8:34   ` Julia Lawall
2022-02-06  9:32   ` Julia Lawall

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