This is a note to let you know that I've just added the patch titled
xen/time: remove blocked time accounting from xen "clockchip"
to the 3.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
xen-time-remove-blocked-time-accounting-from-xen-clockchip.patch
and it can be found in the queue-3.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 0b0c002c340e78173789f8afaa508070d838cf3d Mon Sep 17 00:00:00 2001
From: Laszlo Ersek <[email protected]>
Date: Tue, 18 Oct 2011 22:42:59 +0200
Subject: xen/time: remove blocked time accounting from xen "clockchip"
From: Laszlo Ersek <[email protected]>
commit 0b0c002c340e78173789f8afaa508070d838cf3d upstream.
... because the "clock_event_device framework" already accounts for idle
time through the "event_handler" function pointer in
xen_timer_interrupt().
The patch is intended as the completion of [1]. It should fix the double
idle times seen in PV guests' /proc/stat [2]. It should be orthogonal to
stolen time accounting (the removed code seems to be isolated).
The approach may be completely misguided.
[1] https://lkml.org/lkml/2011/10/6/10
[2] http://lists.xensource.com/archives/html/xen-devel/2010-08/msg01068.html
John took the time to retest this patch on top of v3.10 and reported:
"idle time is correctly incremented for pv and hvm for the normal
case, nohz=off and nohz=idle." so lets put this patch in.
Signed-off-by: Laszlo Ersek <[email protected]>
Signed-off-by: John Haxby <[email protected]>
Signed-off-by: Konrad Rzeszutek Wilk <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/x86/xen/time.c | 17 ++---------------
1 file changed, 2 insertions(+), 15 deletions(-)
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -36,9 +36,8 @@ static DEFINE_PER_CPU(struct vcpu_runsta
/* snapshots of runstate info */
static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate_snapshot);
-/* unused ns of stolen and blocked time */
+/* unused ns of stolen time */
static DEFINE_PER_CPU(u64, xen_residual_stolen);
-static DEFINE_PER_CPU(u64, xen_residual_blocked);
/* return an consistent snapshot of 64-bit time/counter value */
static u64 get64(const u64 *p)
@@ -115,7 +114,7 @@ static void do_stolen_accounting(void)
{
struct vcpu_runstate_info state;
struct vcpu_runstate_info *snap;
- s64 blocked, runnable, offline, stolen;
+ s64 runnable, offline, stolen;
cputime_t ticks;
get_runstate_snapshot(&state);
@@ -125,7 +124,6 @@ static void do_stolen_accounting(void)
snap = &__get_cpu_var(xen_runstate_snapshot);
/* work out how much time the VCPU has not been runn*ing* */
- blocked = state.time[RUNSTATE_blocked] - snap->time[RUNSTATE_blocked];
runnable = state.time[RUNSTATE_runnable] -
snap->time[RUNSTATE_runnable];
offline = state.time[RUNSTATE_offline] - snap->time[RUNSTATE_offline];
@@ -141,17 +139,6 @@ static void do_stolen_accounting(void)
ticks = iter_div_u64_rem(stolen, NS_PER_TICK, &stolen);
__this_cpu_write(xen_residual_stolen, stolen);
account_steal_ticks(ticks);
-
- /* Add the appropriate number of ticks of blocked time,
- including any left-overs from last time. */
- blocked += __this_cpu_read(xen_residual_blocked);
-
- if (blocked < 0)
- blocked = 0;
-
- 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 */
Patches currently in stable-queue which might be from [email protected] are
queue-3.9/xen-time-remove-blocked-time-accounting-from-xen-clockchip.patch
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