From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: Christophe Leroy <christophe.leroy@c-s.fr>,
"Gautham R. Shenoy" <ego@linux.vnet.ibm.com>,
Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Nathan Lynch <nathanl@linux.ibm.com>,
Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
Tyrel Datwyler <tyreld@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] powerpc/sysfs: Show idle_purr and idle_spurr for every CPU
Date: Wed, 05 Feb 2020 13:37:45 +0530 [thread overview]
Message-ID: <1580889776.690kj4ppmj.naveen@linux.ibm.com> (raw)
In-Reply-To: <b26cedb0-8b12-71b6-63d2-990186cd49e5@c-s.fr>
Christophe Leroy wrote:
>
>
> Le 27/11/2019 à 13:01, Gautham R. Shenoy a écrit :
>> From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
>>
>> On Pseries LPARs, to calculate utilization, we need to know the
>> [S]PURR ticks when the CPUs were busy or idle.
>>
>> The total PURR and SPURR ticks are already exposed via the per-cpu
>> sysfs files /sys/devices/system/cpu/cpuX/purr and
>> /sys/devices/system/cpu/cpuX/spurr.
>>
>> This patch adds support for exposing the idle PURR and SPURR ticks via
>> /sys/devices/system/cpu/cpuX/idle_purr and
>> /sys/devices/system/cpu/cpuX/idle_spurr.
>
> Might be a candid question, but I see in arch/powerpc/kernel/time.c that
> PURR/SPURR are already taken into account by the kernel to calculate
> utilisation when CONFIG_VIRT_CPU_ACCOUNTING_NATIVE is selected.
>
> As far as I understand, you are wanting to expose this to userland to
> redo the calculation there. What is wrong with the values reported by
> the kernel ?
As you point out, it is only done with
CONFIG_VIRT_CPU_ACCOUNTING_NATIVE, but isn't available with NO_HZ_FULL,
which happens to be the distro default nowadays.
- Naveen
next prev parent reply other threads:[~2020-02-05 8:09 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-27 12:01 [PATCH 0/3] pseries: Track and expose idle PURR and SPURR ticks Gautham R. Shenoy
2019-11-27 12:01 ` [PATCH 1/3] powerpc/pseries: Account for SPURR ticks on idle CPUs Gautham R. Shenoy
2019-12-03 13:39 ` Kamalesh Babulal
2019-12-04 22:24 ` Nathan Lynch
2020-02-03 4:45 ` Gautham R Shenoy
2019-11-27 12:01 ` [PATCH 2/3] powerpc/sysfs: Show idle_purr and idle_spurr for every CPU Gautham R. Shenoy
2019-12-03 13:37 ` Kamalesh Babulal
2019-12-04 12:37 ` Gautham R Shenoy
2019-12-03 21:02 ` kbuild test robot
2019-12-04 22:24 ` Nathan Lynch
2020-02-03 4:47 ` Gautham R Shenoy
2019-12-05 16:53 ` Naveen N. Rao
2020-02-03 4:50 ` Gautham R Shenoy
2020-02-04 7:52 ` Naveen N. Rao
2020-02-05 4:19 ` Gautham R Shenoy
2020-02-05 6:58 ` Naveen N. Rao
2020-02-05 7:08 ` Christophe Leroy
2020-02-05 8:07 ` Naveen N. Rao [this message]
2019-11-27 12:01 ` [PATCH 3/3] Documentation: Document sysfs interfaces purr, spurr, idle_purr, idle_spurr Gautham R. Shenoy
2019-12-04 22:25 ` Nathan Lynch
2019-12-04 22:24 ` [PATCH 0/3] pseries: Track and expose idle PURR and SPURR ticks Nathan Lynch
2019-12-05 15:03 ` Kamalesh Babulal
2019-12-05 16:16 ` Nathan Lynch
2019-12-05 17:25 ` Naveen N. Rao
2019-12-06 9:14 ` Naveen N. Rao
2020-02-04 9:12 ` Kamalesh Babulal
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