From: "H. Peter Anvin" <hpa@zytor.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Mike Galbraith <bitbucket@online.de>,
Andi Kleen <ak@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] per-cpu preempt_count
Date: Mon, 12 Aug 2013 10:51:43 -0700 [thread overview]
Message-ID: <520920AF.1050407@zytor.com> (raw)
In-Reply-To: <CA+55aFznj9WqGa_Qa0B4=5iTio2br54uJG7xkm6otN2sG2P=8w@mail.gmail.com>
On 08/12/2013 10:35 AM, Linus Torvalds wrote:
>
> Agreed. Making it atomic would suck, and cancel all advantages of the
> better code generation to access it. Good point.
>
> And yeah, it could be two variables in the same cacheline or something.
>
So we would have code looking something like:
decl %fs:preempt_count
jnz 1f
cmpb $0,%fs:need_resched
je 1f
call __preempt_schedule
1:
It's a nontrivial amount of code, but would seem a fair bit better than
what we have now, at least.
-hpa
next prev parent reply other threads:[~2013-08-12 17:53 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-12 11:51 [RFC] per-cpu preempt_count Peter Zijlstra
2013-08-12 17:35 ` Linus Torvalds
2013-08-12 17:51 ` H. Peter Anvin [this message]
2013-08-12 18:53 ` Linus Torvalds
2013-08-13 8:39 ` Peter Zijlstra
2013-08-12 17:58 ` Ingo Molnar
2013-08-12 19:00 ` Linus Torvalds
2013-08-12 20:44 ` H. Peter Anvin
2013-08-13 10:30 ` Ingo Molnar
2013-08-13 12:26 ` Peter Zijlstra
2013-08-13 15:39 ` Linus Torvalds
2013-08-13 15:56 ` Ingo Molnar
2013-08-13 16:26 ` Peter Zijlstra
2013-08-13 16:28 ` H. Peter Anvin
2013-08-13 16:29 ` Peter Zijlstra
2013-08-13 16:38 ` Linus Torvalds
2013-08-18 17:57 ` Paul E. McKenney
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