* [PATCH] xen: ensure timer tick is resumed even on CPU driving the resume [not found] <1274283134.14939.205.camel@zakaz.uk.xensource.com> @ 2010-05-19 15:36 ` Ian Campbell 2010-05-19 18:02 ` [Xen-devel] " Jeremy Fitzhardinge 0 siblings, 1 reply; 4+ messages in thread From: Ian Campbell @ 2010-05-19 15:36 UTC (permalink / raw) Cc: Ian Campbell, xen-devel, linux-kernel, Jeremy Fitzhardinge, stable The core suspend/resume code is run from stop_machine on CPU0 but parts of the suspend/resume machinery (including xen_arch_resume) are run on whichever CPU happened to schedule the xenwatch kernel thread. As part of the non-core resume code xen_arch_resume is called in order to restart the timer tick on non-boot processors. The boot processor itself is taken care of by core timekeeping code. xen_arch_resume uses smp_call_function which does not call the given function on the current processor. This means that we can end up with one CPU not receiving timer ticks if the xenwatch thread happened to be scheduled on CPU > 0. Use on_each_cpu instead of smp_call_function to ensure the timer tick is resumed everywhere. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Stable Kernel <stable@kernel.org> --- arch/x86/xen/suspend.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c index 987267f..a9c6611 100644 --- a/arch/x86/xen/suspend.c +++ b/arch/x86/xen/suspend.c @@ -60,6 +60,6 @@ static void xen_vcpu_notify_restore(void *data) void xen_arch_resume(void) { - smp_call_function(xen_vcpu_notify_restore, - (void *)CLOCK_EVT_NOTIFY_RESUME, 1); + on_each_cpu(xen_vcpu_notify_restore, + (void *)CLOCK_EVT_NOTIFY_RESUME, 1); } -- 1.5.6.5 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [Xen-devel] [PATCH] xen: ensure timer tick is resumed even on CPU driving the resume 2010-05-19 15:36 ` [PATCH] xen: ensure timer tick is resumed even on CPU driving the resume Ian Campbell @ 2010-05-19 18:02 ` Jeremy Fitzhardinge 2010-05-20 17:42 ` Shriram Rajagopalan 0 siblings, 1 reply; 4+ messages in thread From: Jeremy Fitzhardinge @ 2010-05-19 18:02 UTC (permalink / raw) To: Ian Campbell; +Cc: xen-devel, linux-kernel, stable On 05/19/2010 08:36 AM, Ian Campbell wrote: > The core suspend/resume code is run from stop_machine on CPU0 but > parts of the suspend/resume machinery (including xen_arch_resume) are > run on whichever CPU happened to schedule the xenwatch kernel thread. > > As part of the non-core resume code xen_arch_resume is called in order > to restart the timer tick on non-boot processors. The boot processor > itself is taken care of by core timekeeping code. > > xen_arch_resume uses smp_call_function which does not call the given > function on the current processor. This means that we can end up with > one CPU not receiving timer ticks if the xenwatch thread happened to > be scheduled on CPU > 0. > > Use on_each_cpu instead of smp_call_function to ensure the timer tick > is resumed everywhere. > Argh, that seems to be a pretty common trap to fall into. Looks OK (but unfortunately doesn't fix my other problem). Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> J > Signed-off-by: Ian Campbell <ian.campbell@citrix.com> > Cc: Jeremy Fitzhardinge <jeremy@goop.org> > Cc: Stable Kernel <stable@kernel.org> > --- > arch/x86/xen/suspend.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c > index 987267f..a9c6611 100644 > --- a/arch/x86/xen/suspend.c > +++ b/arch/x86/xen/suspend.c > @@ -60,6 +60,6 @@ static void xen_vcpu_notify_restore(void *data) > > void xen_arch_resume(void) > { > - smp_call_function(xen_vcpu_notify_restore, > - (void *)CLOCK_EVT_NOTIFY_RESUME, 1); > + on_each_cpu(xen_vcpu_notify_restore, > + (void *)CLOCK_EVT_NOTIFY_RESUME, 1); > } > ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] xen: ensure timer tick is resumed even on CPU driving the resume 2010-05-19 18:02 ` [Xen-devel] " Jeremy Fitzhardinge @ 2010-05-20 17:42 ` Shriram Rajagopalan 2010-05-20 18:14 ` Jeremy Fitzhardinge 0 siblings, 1 reply; 4+ messages in thread From: Shriram Rajagopalan @ 2010-05-20 17:42 UTC (permalink / raw) To: Jeremy Fitzhardinge; +Cc: stable, xen-devel, Ian Campbell, linux-kernel [-- Attachment #1.1: Type: text/plain, Size: 2270 bytes --] I know this is a long shot but is there an equivalent piece of code in the 2.6.18.8-xen kernel where this patch could be applied ? Assuming that the 2.6.18 also has a similar bug. On Wed, May 19, 2010 at 11:02 AM, Jeremy Fitzhardinge <jeremy@goop.org>wrote: > On 05/19/2010 08:36 AM, Ian Campbell wrote: > > The core suspend/resume code is run from stop_machine on CPU0 but > > parts of the suspend/resume machinery (including xen_arch_resume) are > > run on whichever CPU happened to schedule the xenwatch kernel thread. > > > > As part of the non-core resume code xen_arch_resume is called in order > > to restart the timer tick on non-boot processors. The boot processor > > itself is taken care of by core timekeeping code. > > > > xen_arch_resume uses smp_call_function which does not call the given > > function on the current processor. This means that we can end up with > > one CPU not receiving timer ticks if the xenwatch thread happened to > > be scheduled on CPU > 0. > > > > Use on_each_cpu instead of smp_call_function to ensure the timer tick > > is resumed everywhere. > > > > Argh, that seems to be a pretty common trap to fall into. Looks OK (but > unfortunately doesn't fix my other problem). > > Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> > > J > > > Signed-off-by: Ian Campbell <ian.campbell@citrix.com> > > Cc: Jeremy Fitzhardinge <jeremy@goop.org> > > Cc: Stable Kernel <stable@kernel.org> > > --- > > arch/x86/xen/suspend.c | 4 ++-- > > 1 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c > > index 987267f..a9c6611 100644 > > --- a/arch/x86/xen/suspend.c > > +++ b/arch/x86/xen/suspend.c > > @@ -60,6 +60,6 @@ static void xen_vcpu_notify_restore(void *data) > > > > void xen_arch_resume(void) > > { > > - smp_call_function(xen_vcpu_notify_restore, > > - (void *)CLOCK_EVT_NOTIFY_RESUME, 1); > > + on_each_cpu(xen_vcpu_notify_restore, > > + (void *)CLOCK_EVT_NOTIFY_RESUME, 1); > > } > > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel > -- perception is but an offspring of its own self [-- Attachment #1.2: Type: text/html, Size: 3235 bytes --] [-- Attachment #2: Type: text/plain, Size: 138 bytes --] _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] xen: ensure timer tick is resumed even on CPU driving the resume 2010-05-20 17:42 ` Shriram Rajagopalan @ 2010-05-20 18:14 ` Jeremy Fitzhardinge 0 siblings, 0 replies; 4+ messages in thread From: Jeremy Fitzhardinge @ 2010-05-20 18:14 UTC (permalink / raw) To: Shriram Rajagopalan; +Cc: stable, xen-devel, Ian Campbell, linux-kernel On 05/20/2010 10:42 AM, Shriram Rajagopalan wrote: > I know this is a long shot but is there an equivalent piece of code in > the 2.6.18.8-xen kernel where this patch could be applied ? Assuming > that the 2.6.18 also has a similar bug. Very unlikely. Time is completely different in 2.6.18-xen. J ^ permalink raw reply [flat|nested] 4+ messages in thread
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[not found] <1274283134.14939.205.camel@zakaz.uk.xensource.com>
2010-05-19 15:36 ` [PATCH] xen: ensure timer tick is resumed even on CPU driving the resume Ian Campbell
2010-05-19 18:02 ` [Xen-devel] " Jeremy Fitzhardinge
2010-05-20 17:42 ` Shriram Rajagopalan
2010-05-20 18:14 ` Jeremy Fitzhardinge
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