From: Pavel Machek <pavel@suse.cz>
To: Ingo Molnar <mingo@elte.hu>
Cc: Marin Mitov <mitov@issp.bas.bg>,
LKML <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-rt-users <linux-rt-users@vger.kernel.org>,
akpm@osdl.org, Clark Williams <clark.williams@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
"Luis Claudio R. Goncalves" <lclaudio@uudg.org>,
Gregory Haskins <ghaskins@novell.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andi Kleen <andi-suse@firstfloor.org>
Subject: Re: [PATCH][resubmit] x86: enable preemption in delay
Date: Sat, 28 Jun 2008 12:44:53 +0200 [thread overview]
Message-ID: <20080628104453.GC10872@ucw.cz> (raw)
In-Reply-To: <20080618075518.GD4135@elte.hu>
On Wed 2008-06-18 09:55:18, Ingo Molnar wrote:
>
> * Marin Mitov <mitov@issp.bas.bg> wrote:
>
> > Why not something like that (do keep in mind I am not an expert :-):
> >
> > static void delay_tsc(unsigned long loops)
> > {
> > get and store the mask of allowed cpus;
> > /* prevent the migration */
> > set the mask of allowed cpus to the current cpu only;
> > /* is it possible? could it be guaranteed? */
> > loop for the delay;
> > restore the old mask of allowed cpus;
> > }
> >
> > You have got the idea. Could it be realized? Is it more expensive than
> > the current realization? So, comments, please.
>
> hm, changing/saving/restorig cpus_allowed is really considered a 'heavy'
> operation compared to preempt_disable(). On a 4096 CPUs box cpus_allowed
> is 4096 bits which is half a kilobyte ...
Time to RLE the bitmap?
<runs> Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
prev parent reply other threads:[~2008-07-06 14:47 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-25 18:08 Re:[PATCH -v4] x86: enable preemption in delay Marin Mitov
2008-05-25 19:30 ` Steven Rostedt
2008-05-25 19:58 ` [PATCH " Marin Mitov
2008-05-25 22:21 ` Thomas Gleixner
2008-05-26 5:14 ` [PATCH " Marin Mitov
2008-06-01 16:01 ` [PATCH][resubmit] " Marin Mitov
2008-06-01 16:25 ` Andi Kleen
2008-06-01 17:17 ` Marin Mitov
2008-06-09 12:13 ` Ingo Molnar
2008-06-09 16:11 ` Marin Mitov
2008-06-09 16:16 ` Ingo Molnar
2008-06-15 17:58 ` Marin Mitov
2008-06-18 7:55 ` Ingo Molnar
2008-06-18 12:08 ` Gregory Haskins
2008-06-18 12:13 ` Gregory Haskins
2008-06-18 12:16 ` Peter Zijlstra
2008-06-18 12:25 ` Gregory Haskins
2008-06-18 12:42 ` Nick Piggin
2008-06-18 13:04 ` Gregory Haskins
2008-06-18 16:16 ` Steven Rostedt
2008-06-18 17:18 ` Nick Piggin
2008-06-28 10:44 ` Pavel Machek [this message]
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