From: Con Kolivas <kernel@kolivas.org>
To: "lk" <linux_kernel@patni.com>
Cc: "jeff shia" <tshxiayu@gmail.com>,
linux-kernel@vger.kernel.org, "robert love" <rml@novell.com>
Subject: Re: something about jiffies wraparound overflow
Date: Tue, 27 Dec 2005 20:05:21 +1100 [thread overview]
Message-ID: <200512272005.22440.kernel@kolivas.org> (raw)
In-Reply-To: <003201c60ac3$16692d90$5e91a8c0@patni.com>
On Tuesday 27 December 2005 19:54, lk wrote:
> As you mentioned the code for comparison:
> > /* code 2*/
> > unsigned long timeout = jiffies + HZ/2;
>
> the code has no problem with jiffies wrapping around
> as long as the values are compared in a right way.
> For a 32 bit platform the counter wraps around only once every 50 day
> when the value of HZ 1000. so if your code is prepared to face this event
> it will work fine.
In 2.6 we actually roll over 5 minutes after starting (the jiffy counter is
set to about 5 minutes from roll over); that was put in on purpose to pick up
wraparound bugs easily.
Cheers,
Con
next prev parent reply other threads:[~2005-12-27 9:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-27 4:46 something about jiffies wraparound overflow jeff shia
2005-12-27 8:54 ` lk
2005-12-27 9:05 ` Con Kolivas [this message]
2005-12-27 14:54 ` Ben Collins
[not found] <5oeWK-5Od-11@gated-at.bofh.it>
2005-12-27 10:06 ` Bodo Eggert
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