linux-kernel - [PATCH] cpu idle ticks show twice in xen pvm guest

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Date:	Wed, 5 Oct 2011 22:11:58 -0700 (PDT)
From:	Zhenzhong Duan <zhenzhong.duan@...cle.com>
To:	<linux-x86_64@...r.kernel.org>
Cc:	<linux-kernel@...r.kernel.org>
Subject: [PATCH] cpu idle ticks show twice in xen pvm guest

Run below test on xen pvm.
# x=$(cat /proc/stat | grep cpu0 | awk '{print $5}') && sleep 60  \
&& y=$(cat /proc/stat | grep cpu0 | awk '{print $5}') \
&& echo -e  "X:$x\nY:$y\nIDLE:" $(echo "scale=3; ($y-$x)/6000*100" | bc)

@ X:58562301
@ Y:58574282
@ IDLE: 199.600

Normal idle percent should be around 100%.
xen_timer_interrupt called account_idle_ticks to account hypervisor stolen idle ticks 
but these ticks will be accounted again when idle ticks restarted.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@...cle.com>
Signed-off-by: Joe Jin <joe.jin@...cle.com>

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 163b467..5dcbc91 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -151,7 +151,6 @@ static void do_stolen_accounting(void)
 
 	ticks = iter_div_u64_rem(blocked, NS_PER_TICK, &blocked);
 	__this_cpu_write(xen_residual_blocked, blocked);
-	account_idle_ticks(ticks);
 }
 
 /* Get the TSC speed from Xen */
--
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