From: Ingo Molnar <mingo@kernel.org>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Chris Metcalf <cmetcalf@mellanox.com>,
Thomas Gleixner <tglx@linutronix.de>,
Luiz Capitulino <lcapitulino@redhat.com>,
Christoph Lameter <cl@linux.com>,
"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
Wanpeng Li <kernellwp@gmail.com>, Mike Galbraith <efault@gmx.de>,
Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 6/6] sched/isolation: Tick offload documentation
Date: Fri, 9 Feb 2018 08:06:49 +0100 [thread overview]
Message-ID: <20180209070649.kuk3dbwsycnqugsd@gmail.com> (raw)
In-Reply-To: <1518112779-30196-7-git-send-email-frederic@kernel.org>
* Frederic Weisbecker <frederic@kernel.org> wrote:
> Update the documentation to reflect the 1Hz tick offload changes.
>
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> Cc: Chris Metcalf <cmetcalf@mellanox.com>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Luiz Capitulino <lcapitulino@redhat.com>
> Cc: Mike Galbraith <efault@gmx.de>
> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Rik van Riel <riel@redhat.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Wanpeng Li <kernellwp@gmail.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 39ac9d4..c851e41 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1762,7 +1762,11 @@
> specified in the flag list (default: domain):
>
> nohz
> - Disable the tick when a single task runs.
> + Disable the tick when a single task runs. A residual 1Hz
> + tick is offloaded to workqueues that you need to affine
> + to housekeeping through the sysfs file
> + /sys/devices/virtual/workqueue/cpumask or using the below
> + domain flag.
This is pretty ambiguous and somewhat confusing, I'd suggest something like:
nohz
Disable the tick when a single task runs.
A residual 1Hz tick is offloaded to workqueues, which you
need to affine to housekeeping through the global
workqueue's affinity configured via the
/sys/devices/virtual/workqueue/cpumask sysfs file, or
by using the 'domain' flag described below.
NOTE: by default the global workqueue runs on all CPUs,
so to protect individual CPUs the 'cpumask' file has to
be configured manually after bootup.
Assuming what I wrote is correct - the CPU isolation config space is pretty
confusing all around and should be made a lot more human friendly ...
Thanks,
Ingo
next prev parent reply other threads:[~2018-02-09 7:06 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-08 17:59 [PATCH 0/6] isolation: 1Hz residual tick offloading v5 Frederic Weisbecker
2018-02-08 17:59 ` [PATCH 1/6] sched: Rename init_rq_hrtick to hrtick_rq_init Frederic Weisbecker
2018-02-09 6:53 ` Ingo Molnar
2018-02-08 17:59 ` [PATCH 2/6] nohz: Allow to check if remote CPU tick is stopped Frederic Weisbecker
2018-02-08 17:59 ` [PATCH 3/6] sched/isolation: Isolate workqueues when "nohz_full=" is set Frederic Weisbecker
2018-02-09 6:55 ` Ingo Molnar
2018-02-10 10:22 ` Frederic Weisbecker
2018-02-08 17:59 ` [PATCH 4/6] sched/isolation: Residual 1Hz scheduler tick offload Frederic Weisbecker
2018-02-09 7:16 ` Ingo Molnar
2018-02-10 10:29 ` Frederic Weisbecker
2018-02-08 17:59 ` [PATCH 5/6] sched/nohz: Remove the 1 Hz tick code Frederic Weisbecker
2018-02-08 17:59 ` [PATCH 6/6] sched/isolation: Tick offload documentation Frederic Weisbecker
2018-02-09 7:06 ` Ingo Molnar [this message]
2018-02-14 14:52 ` Frederic Weisbecker
2018-02-09 7:00 ` [PATCH 0/6] isolation: 1Hz residual tick offloading v5 Ingo Molnar
2018-02-10 10:24 ` Frederic Weisbecker
-- strict thread matches above, loose matches on Subject: below --
2018-01-19 0:02 [GIT PULL] isolation: 1Hz residual tick offloading v4 Frederic Weisbecker
2018-01-19 0:02 ` [PATCH 6/6] sched/isolation: Tick offload documentation Frederic Weisbecker
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=20180209070649.kuk3dbwsycnqugsd@gmail.com \
--to=mingo@kernel.org \
--cc=cl@linux.com \
--cc=cmetcalf@mellanox.com \
--cc=efault@gmx.de \
--cc=frederic@kernel.org \
--cc=kernellwp@gmail.com \
--cc=lcapitulino@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=paulmck@linux.vnet.ibm.com \
--cc=peterz@infradead.org \
--cc=riel@redhat.com \
--cc=tglx@linutronix.de \
/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
Powered by JetHome