linux-kernel - Re: [PATCH V5 03/13] perf: Allow pmu to choose cpu on which to install event

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Message-ID: <4FD7F385.1090303@intel.com>
Date:	Wed, 13 Jun 2012 09:57:25 +0800
From:	"Yan, Zheng" <zheng.z.yan@...el.com>
To:	Stephane Eranian <eranian@...gle.com>
CC:	a.p.zijlstra@...llo.nl, mingo@...e.hu, jolsa@...hat.com,
	andi@...stfloor.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V5 03/13] perf: Allow pmu to choose cpu on which to install
 event

On 06/12/2012 06:17 PM, Stephane Eranian wrote:
> On Tue, Jun 12, 2012 at 7:37 AM, Yan, Zheng <zheng.z.yan@...el.com> wrote:
>> From: "Yan, Zheng" <zheng.z.yan@...el.com>
>>
>> Allow the pmu->event_init callback to change event->cpu, so pmu can
>> choose cpu on which to install event.
>>
> So now, the user can say perf record -e xxxx -C 1 -a and then get nothing
> out of perf report -C1 because under the cover the kernel has swapped
> it for another CPU?

This change is for uncore, it does not support 'perf report'.

Regards
Yan, Zheng
> 
>> Signed-off-by: Zheng Yan <zheng.z.yan@...el.com>
>> ---
>>  kernel/events/core.c |    8 ++++----
>>  1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/kernel/events/core.c b/kernel/events/core.c
>> index d71a2d6..2c05027 100644
>> --- a/kernel/events/core.c
>> +++ b/kernel/events/core.c
>> @@ -6302,7 +6302,7 @@ SYSCALL_DEFINE5(perf_event_open,
>>        /*
>>         * Get the target context (task or percpu):
>>         */
>> -       ctx = find_get_context(pmu, task, cpu);
>> +       ctx = find_get_context(pmu, task, event->cpu);
>>        if (IS_ERR(ctx)) {
>>                err = PTR_ERR(ctx);
>>                goto err_alloc;
>> @@ -6375,16 +6375,16 @@ SYSCALL_DEFINE5(perf_event_open,
>>        mutex_lock(&ctx->mutex);
>>
>>        if (move_group) {
>> -               perf_install_in_context(ctx, group_leader, cpu);
>> +               perf_install_in_context(ctx, group_leader, event->cpu);
>>                get_ctx(ctx);
>>                list_for_each_entry(sibling, &group_leader->sibling_list,
>>                                    group_entry) {
>> -                       perf_install_in_context(ctx, sibling, cpu);
>> +                       perf_install_in_context(ctx, sibling, event->cpu);
>>                        get_ctx(ctx);
>>                }
>>        }
>>
>> -       perf_install_in_context(ctx, event, cpu);
>> +       perf_install_in_context(ctx, event, event->cpu);
>>        ++ctx->generation;
>>        perf_unpin_context(ctx);
>>        mutex_unlock(&ctx->mutex);
>> --
>> 1.7.10.2
>>


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