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Message-ID: <4B5ADFC1.6030909@canonical.com>
Date: Sat, 23 Jan 2010 12:38:41 +0100
From: Stefan Bader <stefan.bader@...onical.com>
To: Greg KH <gregkh@...e.de>
CC: linux-kernel@...r.kernel.org, stable@...nel.org,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Ingo Molnar <mingo@...e.hu>, Paul Mackerras <paulus@...ba.org>,
akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
stable-review@...nel.org, alan@...rguk.ukuu.org.uk
Subject: Re: [Stable-review] [28/29] perf events: Dont report side-band events
on each cpu for per-task-per-cpu events
Greg KH wrote:
> 2.6.32-stable review patch. If anyone has any objections, please let us know.
>
> ------------------
>
> From: Peter Zijlstra <a.p.zijlstra@...llo.nl>
>
> commit 5d27c23df09b702868d9a3bff86ec6abd22963ac upstream.
>
> Acme noticed that his FORK/MMAP numbers were inflated by about
> the same factor as his cpu-count.
>
> This led to the discovery of a few more sites that need to
> respect the event->cpu filter.
>
> Reported-by: Arnaldo Carvalho de Melo <acme@...stprotocols.net>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> Cc: Paul Mackerras <paulus@...ba.org>
> LKML-Reference: <20091217121830.215333434@...llo.nl>
> Signed-off-by: Ingo Molnar <mingo@...e.hu>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
>
> ---
> kernel/perf_event.c | 20 ++++++++++++++++++--
> 1 file changed, 18 insertions(+), 2 deletions(-)
>
> --- a/kernel/perf_event.c
> +++ b/kernel/perf_event.c
> @@ -1359,6 +1359,9 @@ static void perf_ctx_adjust_freq(struct
> if (event->state != PERF_EVENT_STATE_ACTIVE)
> continue;
>
> + if (event->cpu != -1 && event->cpu != smp_processor_id())
> + continue;
> +
> hwc = &event->hw;
>
> interrupts = hwc->interrupts;
> @@ -3226,6 +3229,9 @@ static void perf_event_task_output(struc
>
> static int perf_event_task_match(struct perf_event *event)
> {
> + if (event->cpu != -1 && event->cpu != smp_processor_id())
> + return 0;
> +
> if (event->attr.comm || event->attr.mmap || event->attr.task)
> return 1;
>
> @@ -3262,6 +3268,7 @@ static void perf_event_task_event(struct
> ctx = rcu_dereference(task_event->task->perf_event_ctxp);
> if (ctx)
> perf_event_task_ctx(ctx, task_event);
> + put_cpu_var(perf_cpu_context);
> rcu_read_unlock();
> }
I believe this hunk drops the move of put_cpu_var. The upstream hunk looks like
this:
@ -3290,12 +3296,11 @@ static void perf_event_task_event(struct perf_task_event
rcu_read_lock();
cpuctx = &get_cpu_var(perf_cpu_context);
perf_event_task_ctx(&cpuctx->ctx, task_event);
- put_cpu_var(perf_cpu_context);
-
if (!ctx)
ctx = rcu_dereference(task_event->task->perf_event_ctxp);
if (ctx)
perf_event_task_ctx(ctx, task_event);
+ put_cpu_var(perf_cpu_context);
rcu_read_unlock();
}
> @@ -3338,6 +3345,9 @@ static void perf_event_comm_output(struc
>
> static int perf_event_comm_match(struct perf_event *event)
> {
> + if (event->cpu != -1 && event->cpu != smp_processor_id())
> + return 0;
> +
> if (event->attr.comm)
> return 1;
>
> @@ -3378,7 +3388,6 @@ static void perf_event_comm_event(struct
>
> cpuctx = &get_cpu_var(perf_cpu_context);
> perf_event_comm_ctx(&cpuctx->ctx, comm_event);
> - put_cpu_var(perf_cpu_context);
>
> rcu_read_lock();
> /*
> @@ -3388,6 +3397,7 @@ static void perf_event_comm_event(struct
> ctx = rcu_dereference(current->perf_event_ctxp);
> if (ctx)
> perf_event_comm_ctx(ctx, comm_event);
> + put_cpu_var(perf_cpu_context);
> rcu_read_unlock();
> }
>
> @@ -3462,6 +3472,9 @@ static void perf_event_mmap_output(struc
> static int perf_event_mmap_match(struct perf_event *event,
> struct perf_mmap_event *mmap_event)
> {
> + if (event->cpu != -1 && event->cpu != smp_processor_id())
> + return 0;
> +
> if (event->attr.mmap)
> return 1;
>
> @@ -3539,7 +3552,6 @@ got_name:
>
> cpuctx = &get_cpu_var(perf_cpu_context);
> perf_event_mmap_ctx(&cpuctx->ctx, mmap_event);
> - put_cpu_var(perf_cpu_context);
>
> rcu_read_lock();
> /*
> @@ -3549,6 +3561,7 @@ got_name:
> ctx = rcu_dereference(current->perf_event_ctxp);
> if (ctx)
> perf_event_mmap_ctx(ctx, mmap_event);
> + put_cpu_var(perf_cpu_context);
> rcu_read_unlock();
>
> kfree(buf);
> @@ -3811,6 +3824,9 @@ static int perf_swevent_match(struct per
> enum perf_type_id type,
> u32 event_id, struct pt_regs *regs)
> {
> + if (event->cpu != -1 && event->cpu != smp_processor_id())
> + return 0;
> +
> if (!perf_swevent_is_counting(event))
> return 0;
>
>
>
> _______________________________________________
> Stable-review mailing list
> Stable-review@...ux.kernel.org
> http://linux.kernel.org/mailman/listinfo/stable-review
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