From: Edgar Toernig <froese@gmx.de>
To: Andreas Mohr <andi@rhlx01.fht-esslingen.de>
Cc: lkml <linux-kernel@vger.kernel.org>,
john stultz <johnstul@us.ibm.com>,
Dominik Brodowski <linux@brodo.de>
Subject: Re: delay_tsc(): inefficient delay loop (2.6.16-mm1)
Date: Fri, 24 Mar 2006 18:37:42 +0100 [thread overview]
Message-ID: <20060324183742.1b1986d1.froese@gmx.de> (raw)
In-Reply-To: <20060324170436.GA1568@rhlx01.fht-esslingen.de>
Andreas Mohr wrote:
>
> rdtscl(bclock);
> + /* offset with bclock to have very simple comparison below */
> + loops += bclock;
> do {
> rep_nop();
> rdtscl(now);
> - } while ((now-bclock) < loops);
> + } while (now < loops);
> }
Hehe, optimizing delay loops *g* But your optimization is
wrong. 'loops+bclock' and/or 'now' is likely to wrap around
and then the test condition becomes bogus.
Ciao, ET.
prev parent reply other threads:[~2006-03-24 17:37 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-24 17:04 Andreas Mohr
2006-03-24 17:22 ` Ray Lee
2006-03-24 17:41 ` Andreas Mohr
2006-03-24 17:37 ` Edgar Toernig [this message]
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