From: Peter Zijlstra <peterz@infradead.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/1] sched: fix the PREEMPT_ACTIVE check in __trace_sched_switch_state()
Date: Wed, 8 Oct 2014 10:00:16 +0200 [thread overview]
Message-ID: <20141008080016.GB10832@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20141007195046.GA28002@redhat.com>
On Tue, Oct 07, 2014 at 09:50:46PM +0200, Oleg Nesterov wrote:
> And note that another caller of task_preempt_count(), set_cpu(), is
> fine but it doesn't really need this helper.
>
> And afaics we do not need ->saved_preempt_count at all, the trivial
> patch below makes it unnecessary, we can kill it and all its users.
>
> Not only this will simplify the code, this will make (well, almost)
> the per-cpu preempt counter arch-agnostic.
>
> Or I missed something?
Two things, per-cpu isn't always faster on some archs, and load-store
archs have problems with PREEMPT_NEED_RESCHED, although arguably you can
do per-cpu preempt count without that.
> Do you think this makes sense? If yes, I'll try to make the patches.
It penalizes everything but x86 I think. There is no other arch that has
per-cpu preempt count atm.
next prev parent reply other threads:[~2014-10-08 8:00 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-07 19:50 [PATCH 0/1] sched: fix the PREEMPT_ACTIVE check in __trace_sched_switch_state() Oleg Nesterov
2014-10-07 19:51 ` [PATCH 1/1] " Oleg Nesterov
2014-10-10 9:54 ` Peter Zijlstra
2014-10-10 9:56 ` Peter Zijlstra
2014-10-28 11:05 ` [tip:sched/core] sched: Fix " tip-bot for Oleg Nesterov
2014-10-08 8:00 ` Peter Zijlstra [this message]
2014-10-08 18:33 ` [PATCH 0/2] (Was: sched: fix the PREEMPT_ACTIVE check in __trace_sched_switch_state()) Oleg Nesterov
2014-10-08 18:33 ` [PATCH 1/2] sched: schedule_tail() should disable preemption Oleg Nesterov
2014-10-08 19:36 ` [PATCH v2 " Oleg Nesterov
2014-10-08 21:37 ` Kirill Tkhai
2014-10-09 14:57 ` Oleg Nesterov
2014-10-09 15:17 ` Peter Zijlstra
2014-10-09 16:57 ` Oleg Nesterov
2014-10-09 17:28 ` Peter Zijlstra
2014-10-09 17:32 ` Peter Zijlstra
2014-10-09 17:55 ` Oleg Nesterov
2014-10-28 11:06 ` [tip:sched/core] sched: Fix schedule_tail() to " tip-bot for Oleg Nesterov
2014-10-08 18:33 ` [PATCH 2/2] sched: kill task_preempt_count() Oleg Nesterov
2014-10-28 11:06 ` [tip:sched/core] sched: Kill task_preempt_count() tip-bot for Oleg Nesterov
2014-10-09 19:32 ` [PATCH 0/1] sched: make finish_task_switch() return struct rq * Oleg Nesterov
2014-10-09 19:32 ` [PATCH 1/1] " Oleg Nesterov
2014-10-10 10:06 ` Peter Zijlstra
2014-10-10 17:06 ` Oleg Nesterov
2014-10-10 20:32 ` Peter Zijlstra
2014-10-14 17:57 ` Oleg Nesterov
2014-10-28 11:06 ` [tip:sched/core] sched: Make finish_task_switch() return ' struct rq *' tip-bot for Oleg Nesterov
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