From: John Ogness <john.ogness@linutronix.de>
To: Gautam Thaker <ghthaker@gmail.com>, linux-rt-users@vger.kernel.org
Subject: Re: 5.15.28-rt35 #2 SMP PREEMPT_RT: Should scheduling latency be as large as 800 usec?
Date: Wed, 23 Mar 2022 21:09:53 +0106 [thread overview]
Message-ID: <871qyse8ra.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <CA+1+E3UVmbLA76t_JkZMMC6FHsmc_EOKeLztvgN6nAhTjjK5bQ@mail.gmail.com>
On 2022-03-23, Gautam Thaker <ghthaker@gmail.com> wrote:
> I built 5.15.28-rt35 #2 SMP PREEMPT_RT with “Fully Preemptible
> Kernel" option and otherwise using .config from a stock Ubuntu 20.04
> 5.4.0 kernel.
>
> Quick question: I see scheduling/wake_up latencies around 800 usec and
> this is confirmed by cyclictest.
[...]
> node-0> grep -i preempt /boot/config-5.15.28-rt35
> node-0> grep -i debug /boot/config-5.15.28-rt35 |grep =y
[...]
> processor : 31
> vendor_id : GenuineIntel
> cpu family : 6
> model : 63
> model name : Intel(R) Xeon(R) CPU E5-2630 v3 @ 2.40GHz
> stepping : 2
> microcode : 0x46
> cpu MHz : 1200.000
> cache size : 20480 KB
Your CPU is running at 1.2GHz although it is capable of 2.4GHz. This
looks like you have CPU frequency scaling activated. Investigate:
grep -i cpu_freq /boot/config-5.15.28-rt35
The configuration of your tick may also be interesting:
grep -i hz /boot/config-5.15.28-rt35
John Ogness
next prev parent reply other threads:[~2022-03-23 20:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-23 19:35 5.15.28-rt35 #2 SMP PREEMPT_RT: Should scheduling latency be as large as 800 usec? Gautam Thaker
2022-03-23 20:03 ` John Ogness [this message]
2022-03-23 20:16 ` Gautam Thaker
[not found] ` <CAMLffL9hqXcco9NCH1eGdzw4uWPSxPpLaO5fZWgNqS9moKE2HQ@mail.gmail.com>
2022-03-24 0:56 ` Gautam Thaker
2022-03-24 8:55 ` John Ogness
2022-03-24 16:34 ` Gautam Thaker
2022-03-25 8:18 ` John Ogness
2022-03-25 15:50 ` Gautam Thaker
2022-03-25 19:27 ` John Ogness
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=871qyse8ra.fsf@jogness.linutronix.de \
--to=john.ogness@linutronix.de \
--cc=ghthaker@gmail.com \
--cc=linux-rt-users@vger.kernel.org \
/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