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| Started by | Anna-Maria Gleixner <anna-maria@linutronix.de> |
|---|---|
| First post | 2016-03-11 12:00 +0100 |
| Last post | 2016-03-14 16:50 +0100 |
| Articles | 5 — 3 participants |
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[PATCH 0/2] s390: Hotplug notifier transitions Anna-Maria Gleixner <anna-maria@linutronix.de> - 2016-03-11 12:00 +0100
[PATCH 2/2] s390/cpum_sf: Fix cpu hotplug notifier transitions Anna-Maria Gleixner <anna-maria@linutronix.de> - 2016-03-11 12:00 +0100
Re: [PATCH 2/2] s390/cpum_sf: Fix cpu hotplug notifier transitions Heiko Carstens <heiko.carstens@de.ibm.com> - 2016-03-14 10:00 +0100
Re: [PATCH 2/2] s390/cpum_sf: Fix cpu hotplug notifier transitions Hendrik Brueckner <brueckner@linux.vnet.ibm.com> - 2016-03-14 15:50 +0100
Re: [PATCH 0/2] s390: Hotplug notifier transitions Heiko Carstens <heiko.carstens@de.ibm.com> - 2016-03-14 16:50 +0100
| From | Anna-Maria Gleixner <anna-maria@linutronix.de> |
|---|---|
| Date | 2016-03-11 12:00 +0100 |
| Subject | [PATCH 0/2] s390: Hotplug notifier transitions |
| Message-ID | <rbsXw-4QJ-17@gated-at.bofh.it> |
The following patches fix missing error handling of hotplug notifier transitions. Thanks, Anna-Maria --- perf_cpum_cf.c | 1 + perf_cpum_sf.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-)
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| From | Anna-Maria Gleixner <anna-maria@linutronix.de> |
|---|---|
| Date | 2016-03-11 12:00 +0100 |
| Subject | [PATCH 2/2] s390/cpum_sf: Fix cpu hotplug notifier transitions |
| Message-ID | <rbsXw-4QJ-33@gated-at.bofh.it> |
| In reply to | #1355813 |
The cpumf_pmu_notfier() hotplug callback lacks handling of the
CPU_DOWN_FAILED case. That means, if CPU_DOWN_PREPARE failes, the PMC
of the CPU is not setup again. Furthermore the CPU_ONLINE_FROZEN case
will never be processed because of masking the switch expression with
CPU_TASKS_FROZEN.
Add handling for CPU_DOWN_FAILED transition to setup the PMC of the
CPU. Remove CPU_ONLINE_FROZEN case.
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
arch/s390/kernel/perf_cpum_sf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/s390/kernel/perf_cpum_sf.c
+++ b/arch/s390/kernel/perf_cpum_sf.c
@@ -1518,7 +1518,7 @@ static int cpumf_pmu_notifier(struct not
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_ONLINE:
- case CPU_ONLINE_FROZEN:
+ case CPU_DOWN_FAILED:
flags = PMC_INIT;
smp_call_function_single(cpu, setup_pmc_cpu, &flags, 1);
break;
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| From | Heiko Carstens <heiko.carstens@de.ibm.com> |
|---|---|
| Date | 2016-03-14 10:00 +0100 |
| Subject | Re: [PATCH 2/2] s390/cpum_sf: Fix cpu hotplug notifier transitions |
| Message-ID | <rcww1-1qc-11@gated-at.bofh.it> |
| In reply to | #1355818 |
On Fri, Mar 11, 2016 at 11:52:38AM +0100, Anna-Maria Gleixner wrote:
> The cpumf_pmu_notfier() hotplug callback lacks handling of the
> CPU_DOWN_FAILED case. That means, if CPU_DOWN_PREPARE failes, the PMC
> of the CPU is not setup again. Furthermore the CPU_ONLINE_FROZEN case
> will never be processed because of masking the switch expression with
> CPU_TASKS_FROZEN.
>
> Add handling for CPU_DOWN_FAILED transition to setup the PMC of the
> CPU. Remove CPU_ONLINE_FROZEN case.
>
> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> Cc: linux-s390@vger.kernel.org
> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
> ---
> arch/s390/kernel/perf_cpum_sf.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/arch/s390/kernel/perf_cpum_sf.c
> +++ b/arch/s390/kernel/perf_cpum_sf.c
> @@ -1518,7 +1518,7 @@ static int cpumf_pmu_notifier(struct not
>
> switch (action & ~CPU_TASKS_FROZEN) {
> case CPU_ONLINE:
> - case CPU_ONLINE_FROZEN:
> + case CPU_DOWN_FAILED:
> flags = PMC_INIT;
> smp_call_function_single(cpu, setup_pmc_cpu, &flags, 1);
> break;
This is a bit odd, but independent from your patch: setup_pmc_cpu() will
only deallocate buffers but not allocate them.
Looking at the code a bit further this seems to imply that sampling will
not work on cpus that were added later.
Hendrik, could you please have a look?
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| From | Hendrik Brueckner <brueckner@linux.vnet.ibm.com> |
|---|---|
| Date | 2016-03-14 15:50 +0100 |
| Subject | Re: [PATCH 2/2] s390/cpum_sf: Fix cpu hotplug notifier transitions |
| Message-ID | <rcBYJ-511-9@gated-at.bofh.it> |
| In reply to | #1357077 |
On Mon, Mar 14, 2016 at 09:51:50AM +0100, Heiko Carstens wrote:
> On Fri, Mar 11, 2016 at 11:52:38AM +0100, Anna-Maria Gleixner wrote:
> > The cpumf_pmu_notfier() hotplug callback lacks handling of the
> > CPU_DOWN_FAILED case. That means, if CPU_DOWN_PREPARE failes, the PMC
> > of the CPU is not setup again. Furthermore the CPU_ONLINE_FROZEN case
> > will never be processed because of masking the switch expression with
> > CPU_TASKS_FROZEN.
> >
> > Add handling for CPU_DOWN_FAILED transition to setup the PMC of the
> > CPU. Remove CPU_ONLINE_FROZEN case.
> >
> > Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
> > Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> > Cc: linux-s390@vger.kernel.org
> > Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
> > ---
> > arch/s390/kernel/perf_cpum_sf.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > --- a/arch/s390/kernel/perf_cpum_sf.c
> > +++ b/arch/s390/kernel/perf_cpum_sf.c
> > @@ -1518,7 +1518,7 @@ static int cpumf_pmu_notifier(struct not
> >
> > switch (action & ~CPU_TASKS_FROZEN) {
> > case CPU_ONLINE:
> > - case CPU_ONLINE_FROZEN:
> > + case CPU_DOWN_FAILED:
The change looks ok for me.
Acked-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
> > flags = PMC_INIT;
> > smp_call_function_single(cpu, setup_pmc_cpu, &flags, 1);
> > break;
>
> This is a bit odd, but independent from your patch: setup_pmc_cpu() will
> only deallocate buffers but not allocate them.
That's right. Allocation is done when an perf event is about to be scheduled
on a CPU.
>
> Looking at the code a bit further this seems to imply that sampling will
> not work on cpus that were added later.
That might be a problem for task-based perf events. I will have a closer
look into that issue.
Many thanks.
Kind regards,
Hendrik
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| From | Heiko Carstens <heiko.carstens@de.ibm.com> |
|---|---|
| Date | 2016-03-14 16:50 +0100 |
| Message-ID | <rcCUP-5IT-25@gated-at.bofh.it> |
| In reply to | #1355813 |
On Fri, Mar 11, 2016 at 11:52:36AM +0100, Anna-Maria Gleixner wrote: > The following patches fix missing error handling of hotplug notifier > transitions. > > Thanks, > Anna-Maria > > --- > perf_cpum_cf.c | 1 + > perf_cpum_sf.c | 2 +- > 2 files changed, 2 insertions(+), 1 deletion(-) Applied, thanks!
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