From: Nathan Lynch <nathanl@linux.ibm.com>
To: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
Michael Ellerman <mpe@ellerman.id.au>,
Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
Tyrel Datwyler <tyreld@linux.ibm.com>,
"Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
Subject: Re: [PATCH 0/3] pseries: Track and expose idle PURR and SPURR ticks
Date: Thu, 05 Dec 2019 10:16:19 -0600 [thread overview]
Message-ID: <87k17au4rw.fsf@linux.ibm.com> (raw)
In-Reply-To: <48823589-b105-0da3-e532-f633ade8f0d9@linux.vnet.ibm.com>
Hi Kamalesh,
Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> writes:
> On 12/5/19 3:54 AM, Nathan Lynch wrote:
>> "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> writes:
>>>
>>> Tools such as lparstat which are used to compute the utilization need
>>> to know [S]PURR ticks when the cpu was busy or idle. The [S]PURR
>>> counters are already exposed through sysfs. We already account for
>>> PURR ticks when we go to idle so that we can update the VPA area. This
>>> patchset extends support to account for SPURR ticks when idle, and
>>> expose both via per-cpu sysfs files.
>>
>> Does anything really want to use PURR instead of SPURR? Seems like we
>> should expose only SPURR idle values if possible.
>>
>
> lparstat is one of the consumers of PURR idle metric
> (https://groups.google.com/forum/#!topic/powerpc-utils-devel/fYRo69xO9r4).
> Agree, on the argument that system utilization metrics based on SPURR
> accounting is accurate in comparison to PURR, which isn't proportional to
> CPU frequency. PURR has been traditionally used to understand the system
> utilization, whereas SPURR is used for understanding how much capacity is
> left/exceeding in the system based on the current power saving mode.
I'll phrase my question differently: does SPURR complement or supercede
PURR? You seem to be saying they serve different purposes. If PURR is
actually useful rather then vestigial then I have no objection to
exposing idle_purr.
next prev parent reply other threads:[~2019-12-05 16:16 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
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 [this message]
2019-12-05 17:25 ` Naveen N. Rao
2019-12-06 9:14 ` Naveen N. Rao
2020-02-04 9:12 ` Kamalesh Babulal
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87k17au4rw.fsf@linux.ibm.com \
--to=nathanl@linux.ibm.com \
--cc=ego@linux.vnet.ibm.com \
--cc=kamalesh@linux.vnet.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=naveen.n.rao@linux.vnet.ibm.com \
--cc=svaidy@linux.vnet.ibm.com \
--cc=tyreld@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).