From: Peter Zijlstra <peterz@infradead.org>
To: Kirill Tkhai <tkhai@yandex.ru>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH] spin_unlock*_no_resched()
Date: Tue, 18 Jun 2013 12:05:41 +0200 [thread overview]
Message-ID: <20130618100541.GN3204@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1022041371038807@web30d.yandex.ru>
On Wed, Jun 12, 2013 at 04:06:47PM +0400, Kirill Tkhai wrote:
> There are many constructions like:
>
> spin_unlock_irq(lock);
> schedule();
>
> In case of preemptible kernel we check if task needs reschedule
> at the end of spin_unlock(). So if TIF_NEED_RESCHED is set
> we call schedule() twice and we have a little overhead here.
> Add primitives to avoid these situations.
>
Aside from the excellent comments you received from Steven, please also
include a patch that converts some (if not all) of these many callsites
you found so that there's a user of the new code in the kernel.
That way we can simply build + run the kernel and have more confidence
things work as supposed.
prev parent reply other threads:[~2013-06-18 10:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-12 12:06 [PATCH] spin_unlock*_no_resched() Kirill Tkhai
2013-06-12 12:15 ` Peter Zijlstra
2013-06-12 13:07 ` Steven Rostedt
2013-06-12 23:06 ` Kirill Tkhai
2013-06-13 0:07 ` Kirill Tkhai
2013-06-18 10:05 ` Peter Zijlstra [this message]
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