From: Michal Hocko <mhocko@suse.com>
To: Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbecker@suse.de>,
LKML <linux-kernel@vger.kernel.org>, Mel Gorman <mgorman@suse.de>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: [RFC PATCH] kernel: allow to configure PREEMPT_NONE, PREEMPT_VOLUNTARY on kernel command line
Date: Fri, 9 Oct 2020 11:12:18 +0200 [thread overview]
Message-ID: <20201009091218.GF4967@dhcp22.suse.cz> (raw)
In-Reply-To: <20201007120401.11200-1-mhocko@kernel.org>
On Wed 07-10-20 14:04:01, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> Many people are still relying on pre built distribution kernels and so
> distributions have to provide mutliple kernel flavors to offer different
> preemption models. Most of them are providing PREEMPT_NONE for typical
> server deployments and PREEMPT_VOLUNTARY for desktop users.
>
> Having two different kernel binaries differing only by the preemption
> mode seems rather wasteful and inflexible. Especially when the difference
> between PREEMPT_NONE and PREEMPT_VOLUNTARY is really minimal. Both only
> allow explicit scheduling points while running in the kernel and it is
> only might_sleep which adds additional preemption points for
> PREEMPT_VOLUNTARY.
>
> Add a kernel command line parameter preempt_mode=[none, voluntary] which
> allows to override the default compile time preemption mode
> (CONFIG_PREEMPT_NONE resp. CONFIG_PREEMPT_VOLUTARY). Voluntary preempt
> mode is guarded by a jump label to prevent any potential runtime overhead.
>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>
> Hi all,
> this is sent as an RFC because it still needs some work. E.g. move jump
> label changes into their own patch. They are needed mostly to get rid of
> header files dependencies (seen for CONFIG_JUMP_LABEL=n via atomic.h ->
> bug.h).
>
> I wanted to make sure that the idea is sound for maintainers first. The
> next step would be extending the command line to support full preemption
> as well but there is much more work in that area. Frederic has promissed
> to look into that.
>
> Thoughts?
Is there any additional feedback? Should I split up the patch and repost
for inclusion?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-10-09 9:12 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-07 12:04 [RFC PATCH] kernel: allow to configure PREEMPT_NONE, PREEMPT_VOLUNTARY on kernel command line Michal Hocko
2020-10-07 12:19 ` Peter Zijlstra
2020-10-07 12:29 ` Michal Hocko
2020-10-07 13:01 ` Mel Gorman
2020-10-07 12:21 ` Peter Zijlstra
2020-10-07 12:35 ` Michal Hocko
2020-10-09 9:47 ` Peter Zijlstra
2020-10-09 10:14 ` Michal Hocko
2020-10-09 10:20 ` Peter Zijlstra
2020-10-09 10:48 ` Michal Hocko
2020-10-09 11:17 ` Michal Hocko
2020-10-09 11:26 ` Michal Hocko
2020-10-09 11:39 ` Peter Zijlstra
2020-10-09 9:12 ` Michal Hocko [this message]
2020-10-09 9:42 ` Peter Zijlstra
2020-10-09 10:10 ` Michal Hocko
2020-10-09 10:14 ` Peter Zijlstra
2020-10-09 10:37 ` Michal Hocko
2020-10-09 11:42 ` Peter Zijlstra
2020-10-09 12:29 ` [RFC PATCH v2 0/5] allow overriding default preempt mode from " Michal Hocko
2020-10-09 12:29 ` [RFC PATCH v2 1/5] jump_label: split out declaration parts into its own headers Michal Hocko
2020-10-09 12:29 ` [RFC PATCH v2 2/5] kernel: allow to configure PREEMPT_NONE, PREEMPT_VOLUNTARY on kernel command line Michal Hocko
2020-10-09 12:29 ` [RFC PATCH v2 3/5] kernel: ARCH_NO_PREEMPT shouldn't exclude PREEMPT_VOLUNTARY Michal Hocko
2020-10-09 12:29 ` [RFC PATCH v2 4/5] kernel: introduce CONFIG_PREEMPT_DYNAMIC Michal Hocko
2020-10-09 12:29 ` [RFC PATCH v2 5/5] kernel: drop PREEMPT_NONE compile time option Michal Hocko
2020-10-09 12:50 ` [RFC PATCH v2 0/5] allow overriding default preempt mode from command line Peter Zijlstra
2020-10-09 13:03 ` Michal Hocko
2020-10-09 13:22 ` Peter Zijlstra
2020-10-09 17:45 ` Peter Zijlstra
2020-10-27 12:22 ` Frederic Weisbecker
2020-10-27 12:28 ` Peter Zijlstra
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