From: David Miller <davem@davemloft.net>
To: tglx@linutronix.de
Cc: michal.k.k.piotrowski@gmail.com, torvalds@linux-foundation.org,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
mingo@elte.hu
Subject: Re: [PATCH] NOHZ: prevent multiplication overflow - stop timer for huge timeouts
Date: Tue, 29 May 2007 16:02:33 -0700 (PDT) [thread overview]
Message-ID: <20070529.160233.45506339.davem@davemloft.net> (raw)
In-Reply-To: <1180475259.20546.26.camel@chaos>
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 29 May 2007 23:47:39 +0200
> get_next_timer_interrupt() returns a delta of (LONG_MAX > 1) in case
> there is no timer pending. On 64 bit machines this results in a
> multiplication overflow in tick_nohz_stop_sched_tick().
>
> Reported by: Dave Miller <davem@davemloft.net>
>
> Make the return value a constant and limit the return value to a 32 bit
> value.
>
> When the max timeout value is returned, we can safely stop the tick
> timer device. The max jiffies delta results in a 12 days timeout for
> HZ=1000.
>
> In the long term the get_next_timer_interrupt() code needs to be
> reworked to return ktime instead of jiffies, but we have to wait until
> the last users of the original NO_IDLE_HZ code are converted.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-off-by: David S. Miller <davem@davemloft.net>
next prev parent reply other threads:[~2007-05-29 23:02 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <465C188F.9000900@googlemail.com>
2007-05-29 12:52 ` [3/4] 2.6.22-rc3: known regressions Michal Piotrowski
2007-05-29 21:47 ` [PATCH] NOHZ: prevent multiplication overflow - stop timer for huge timeouts Thomas Gleixner
2007-05-29 23:02 ` David Miller [this message]
2007-05-31 2:33 ` [3/4] 2.6.22-rc3: known regressions Linus Torvalds
2007-05-31 4:51 ` Antonino A. Daplas
2007-05-31 5:54 ` Tero Roponen
2007-05-31 6:04 ` [PATCH] neofb: Fix pseudo_palette array overrun in neofb_setcolreg Antonino A. Daplas
2007-06-05 11:09 ` Antonino A. Daplas
2007-06-05 11:34 ` [PATCH] [RESEND] " Antonino A. Daplas
2007-05-29 12:53 ` [4/4] 2.6.22-rc3: known regressions Michal Piotrowski
2007-06-09 11:38 ` Mauro Carvalho Chehab
2007-05-29 12:56 ` [2/4] " Michal Piotrowski
2007-05-29 15:01 ` Stephen Hemminger
2007-05-31 2:22 ` Linus Torvalds
2007-05-31 22:08 ` Mike Miller (OS Dev)
2007-05-31 22:22 ` Linus Torvalds
2007-05-31 22:39 ` Mike Miller (OS Dev)
2007-05-31 22:50 ` Andrew Morton
2007-05-31 23:12 ` Linus Torvalds
2007-05-31 23:17 ` Roland Dreier
2007-05-31 23:34 ` Andrew Morton
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