From: Andi Kleen <andi@firstfloor.org>
To: Marin Mitov <mitov@issp.bas.bg>
Cc: 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, 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>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andi Kleen <andi-suse@firstfloor.org>
Subject: Re: [PATCH][resubmit] x86: enable preemption in delay
Date: Sun, 1 Jun 2008 18:25:17 +0200 [thread overview]
Message-ID: <20080601162517.GH20824@one.firstfloor.org> (raw)
In-Reply-To: <200806011901.23619.mitov@issp.bas.bg>
> static void delay_tsc(unsigned long loops)
> {
> - unsigned long bclock, now;
> + unsigned prev, prev_1, now;
> + unsigned left = loops;
> + unsigned prev_cpu, cpu;
> +
> + preempt_disable();
> + rdtscl(prev);
The unsigneds should be probably u64 and the rdtsc rdtscll.
Otherwise this will all overflow for longer waits on a very
fast systems (e.g. a 5Ghz system wraps 32bit in ~1.1 seconds)
Normally such delays shouldn't be that long, but why risk
overflow even in extreme cases?
-Andi
next prev parent reply other threads:[~2008-06-01 16:16 UTC|newest]
Thread overview: 23+ 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 16:01 ` Marin Mitov
2008-06-01 16:25 ` Andi Kleen [this message]
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
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