From: Pavel Machek <pavel@ucw.cz>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
linux-rt-users <linux-rt-users@vger.kernel.org>,
akpm@osdl.org, Ingo Molnar <mingo@elte.hu>,
Clark Williams <clark.williams@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
"Luis Claudio R. Goncalves" <lclaudio@uudg.org>,
Gregory Haskins <ghaskins@novell.com>, Andi Kleen <ak@suse.de>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] x86: enable preemption in delay
Date: Sat, 31 May 2008 09:18:18 +0200 [thread overview]
Message-ID: <20080531071817.GB5405@ucw.cz> (raw)
In-Reply-To: <Pine.LNX.4.58.0805280855250.25179@gandalf.stny.rr.com>
On Wed 2008-05-28 09:01:06, Steven Rostedt wrote:
>
>
> On Sun, 25 May 2008, Pavel Machek wrote:
> > > + if (unlikely(cpu != smp_processor_id())) {
> > > + if (loops <= TSC_MIGRATE_COUNT)
> > > + break;
> > > + cpu = smp_processor_id();
> > > + rdtscl(bclock);
> > > + loops -= TSC_MIGRATE_COUNT;
> > > + } else {
> > > + rdtscl(now);
> > > + if ((now - bclock) >= loops)
> > > + break;
> > > + loops -= (now - bclock);
> > > + bclock = now;
> >
> > What happens with different cpus running on different frequencies...?
> > Cpufreq?
>
> It's not even protected with the old code.
Maybe, but it is simple to fix as long as preemption is disabled. When
you enable it, it becomes much harder.
Lets get that fixed.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2008-06-01 14:18 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-25 3:11 Steven Rostedt
2008-05-25 12:44 ` Thomas Gleixner
2008-05-25 13:07 ` Steven Rostedt
2008-05-25 13:17 ` Steven Rostedt
2008-05-25 13:19 ` Alan Cox
2008-05-25 13:40 ` Steven Rostedt
2008-05-25 20:21 ` Thomas Gleixner
2008-05-25 13:35 ` [PATCH -v2] " Steven Rostedt
2008-05-25 13:44 ` Steven Rostedt
2008-05-25 13:51 ` [PATCH -v3] " Steven Rostedt
2008-05-25 15:04 ` Steven Rostedt
2008-05-25 15:13 ` [PATCH -v4] " Steven Rostedt
2008-05-25 18:01 ` [PATCH] " Pavel Machek
2008-05-28 13:01 ` Steven Rostedt
2008-05-31 7:18 ` Pavel Machek [this message]
2008-05-25 18:53 ` Arjan van de Ven
2008-05-25 19:01 ` Thomas Gleixner
2008-05-25 19:28 ` Arjan van de Ven
2008-05-25 19:32 ` Steven Rostedt
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