From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: aneesh.kumar@kernel.org, npiggin@gmail.com,
naveen.n.rao@linux.ibm.com, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/pseries: fix accuracy of stolen time
Date: Tue, 13 Feb 2024 11:42:45 +0530 [thread overview]
Message-ID: <20240213061245.GB243379@linux.vnet.ibm.com> (raw)
In-Reply-To: <20240213052635.231597-1-sshegde@linux.ibm.com>
* Shrikanth Hegde <sshegde@linux.ibm.com> [2024-02-13 10:56:35]:
> powerVM hypervisor updates the VPA fields with stolen time data.
> It currently reports enqueue_dispatch_tb and ready_enqueue_tb for
> this purpose. In linux these two fields are used to report the stolen time.
>
> The VPA fields are updated at the TB frequency. On powerPC its mostly
> set at 512Mhz. Hence this needs a conversion to ns when reporting it
> back as rest of the kernel timings are in ns. This conversion is already
> handled in tb_to_ns function. So use that function to report accurate
> stolen time.
>
> Observed this issue and used an Capped Shared Processor LPAR(SPLPAR) to
> simplify the experiments. In all these cases, 100% VP Load is run using
> stress-ng workload. Values of stolen time is in percentages as reported
> by mpstat. With the patch values are close to expected.
>
> 6.8.rc1 +Patch
> 12EC/12VP 0.0 0.0
> 12EC/24VP 25.7 50.2
> 12EC/36VP 37.3 69.2
> 12EC/48VP 38.5 78.3
>
>
> Fixes: 0e8a63132800 ("powerpc/pseries: Implement CONFIG_PARAVIRT_TIME_ACCOUNTING")
> Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Looks good to me.
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
--
Thanks and Regards
Srikar Dronamraju
next prev parent reply other threads:[~2024-02-13 6:13 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-13 5:26 [PATCH] powerpc/pseries: fix accuracy of stolen time Shrikanth Hegde
2024-02-13 5:53 ` Nicholas Piggin
2024-02-13 6:12 ` Srikar Dronamraju [this message]
2024-02-15 12:57 ` Michael Ellerman
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=20240213061245.GB243379@linux.vnet.ibm.com \
--to=srikar@linux.vnet.ibm.com \
--cc=aneesh.kumar@kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=naveen.n.rao@linux.ibm.com \
--cc=npiggin@gmail.com \
--cc=sshegde@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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.