From: Peter Zijlstra <peterz@infradead.org>
To: Michal Hocko <mhocko@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
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 12:20:09 +0200 [thread overview]
Message-ID: <20201009102009.GK2628@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20201009101405.GI4967@dhcp22.suse.cz>
On Fri, Oct 09, 2020 at 12:14:05PM +0200, Michal Hocko wrote:
> On Fri 09-10-20 11:47:41, Peter Zijlstra wrote:
> > That is, work backwards (from PREEMPT back to VOLUNTARY) instead of the
> > other way around.
>
> My original idea was that the config would only define the default
> preemption mode. preempt_none parameter would then just act as an
> override. That would mean that CONFIG_PREEMPTION would be effectively
> gone from the kernel. The reason being that any code outside of the
> scheduler shouldn't really care about the preemption mode. I suspect
> this will prevent from dubious hacks and provide a more robust code in
> the end.
Sure; but the way of arriving at that destination might be easier if
you work backwards from PREEMPT=y, because while there _should_ not be
dependencies outside of the scheduler, we both know there are.
This also makes your patches independent of the series that makes
CONFIG_PREEMPTION unconditional.
It also gives Kconfig space to limit the dynamic thing to archs that
have sufficient support (we'll be relying on static_call/static_branch,
and not everybody has that implemented in a way that makes it the
dynamic change worth-while).
next prev parent reply other threads:[~2020-10-09 10:20 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 [this message]
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
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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