Re: LIO/sec per CPU limit? Is it Hardware or Oracle code?

Well, one final(?) piece of information. On Friday, one of the slow boxes was rebooted. After it came back up I ran turbostat and the. J.Lewis cpu heavy SQL. The turbostat output had PKG_% (RAPL throttling) at 0 and the SQL ran at the fast server speed (~20sec intead of 50). So a reboot seemed to flip something back. Not a really satisfying answer as I don't know what started this to begin with and have no way to tell if it will happen again.
Thanks for all your help.

Henry

On Sep 5, 2017 09:32, "Henry Poras" <henry.poras_at_gmail.com> wrote:

> Stefen,
> If I didn't post the kernel, I should have
>
> $uname -r
> 2.6.32-696.1.1.e16.x86_64
>
> All I know about perf is that the fiber cards had driver issues with newer
> kernels which is what is preventing the installation of perf.
>
> I'll take a look at some of your links.
>
> Thanks for the pointers.
>
> Henry
>
> On Sep 5, 2017 5:15 AM, "Stefan Koehler" <contact_at_soocs.de> wrote:
>
>> Hello Henry,
>>
>> > 1. Our sysadm said that there are kernel issues and "perf stat" cannot
>> run on these systems
>>
>> I really would like to hear about these kernel issues and his concerns -
>> never seen an issue with these.
>>
>>
>> > Also RAPL throttling is on in the slow server. I am guessing this could
>> account for the throttled cpu speed. I am starting to google search to see
>> where this can be set from. Anyone out there know any good resources on
>> RAPL throttling or how to disable it?
>>
>> Unfortunately you have not mentioned your linux kernel version yet (or i
>> just missed it) but there are several ways to drill down into RAPL.
>>
>> 1) PowerCap interface: https://www.kernel.org/doc/Doc
>> umentation/power/powercap/powercap.txt
>> 2) Perf
>> 3) MSR registers (/dev/msr)
>>
>> However if you can do the fancy stuff at all depends on BIOS (and
>> vendor). If you run dmesg you may see some messages about "intel_rapl" to
>> get an idea if it works anyway with your hardware.
>>
>> Best Regards
>> Stefan Koehler
>>
>> Independent Oracle performance consultant and researcher
>> Website: http://www.soocs.de
>> Twitter: _at_OracleSK
>>
>> > Henry Poras <henry.poras_at_gmail.com> hat am 5. September 2017 um 06:39
>> geschrieben:
>> >
>> > Figured it was time to send the list an update.
>> > 1. Our sysadm said that there are kernel issues and "perf stat" cannot
>> run on these systems
>> > 2. I installed a slob instance on both a fast and slow server. There
>> was no way to stop our workload from running, but I ran slob multiple
>> times, trying to keep each run short (~3 minutes) so the underlying
>> workload would not vary much. Also tried running when the load was
>> relatively low. All of the run results were pretty consistent with one
>> another. Configuring SLOB to run strictly LIO, I saw ~4M lio/sec vs. 1.5M
>> lio/sec
>> > 3. Our sysadm did get turbostat installed. What I take as the most
>> important output from that was:
>> > slow: TSC_MHz - 2600 Bzy_MHz - 1200 PKG_% - 100%
>> > fast: TSC_MHz - 2606 Bzy_MHz - 3110 PKG_% - 0%
>> >
>> > So the clock speeds are nearly identical, ,but the running speeds when
>> busy are very different. Also RAPL throttling is on in the slow server. I
>> am guessing this could account for the throttled cpu speed. I am starting
>> to google search to see where this can be set from. Anyone out there know
>> any good resources on RAPL throttling or how to disable it?
>> >
>> > Thanks.
>> >
>> > Henry
>>
>

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