Attachment 317208 Details for Bug 462853 – backport of upstream patch that rounds up sleep

[patch] backport of upstream patch that rounds up sleep

linux-2.6-xen-sleep-roundup.patch (text/plain), 1.05 KB, created by Rik van Riel on 2008-09-19 16:01:00 UTC

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Creator: Rik van Riel

Created: 2008-09-19 16:01:00 UTC

Size: 1.05 KB

patch

obsolete

>A simple backport of an upstream changeset that rounds up
>the number of jiffies we sleep.  This prevents the kernel
>from being woken up just before the sleep completes, avoiding
>early wakeups and/or spinning between kernel and hypervisor.
>
>Fixes bug 462853
>
># HG changeset patch
># User Keir Fraser <keir.fraser@citrix.com>
># Date 1212170930 -3600
># Node ID 557a4a0a5eacb83ffb2808c66fd9674e8e26f3e0
># Parent  936f6dd9d49c71c95931c9d8bdf4393cdb9fb42f
>xen: Set blocking timeout to 1/2 jiffy later than we want. This avoids
>repeated early wakeup just before the jiffy tick, causing us to
>effectively spin rather than sleep.
>
>Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
>
>--- linux-2.6.18.noarch/arch/i386/kernel/time-xen.c.roundup	2008-09-19 11:23:08.000000000 -0400
>+++ linux-2.6.18.noarch/arch/i386/kernel/time-xen.c	2008-09-19 11:39:11.000000000 -0400
>@@ -1015,7 +1015,7 @@ static void stop_hz_timer(void)
> 		j = jiffies + 1;
> 	}
> 
>-	if (HYPERVISOR_set_timer_op(jiffies_to_st(j)) != 0)
>+	if (HYPERVISOR_set_timer_op(jiffies_to_st(j) + NS_PER_TICK/2) != 0)
> 		BUG();
> }
>

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Attachments on bug 462853: 317183 | 317208