From: Paul Mackerras <paulus@samba.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Stephane Eranian <eranian@google.com>,
Will Deacon <will.deacon@arm.com>,
Paul Mundt <lethal@linux-sh.org>,
David Miller <davem@davemloft.net>,
Borislav Petkov <bp@amd64.org>
Subject: Re: [RFC PATCH 5/6 v4] perf: Fix race in callchains
Date: Tue, 17 Aug 2010 14:53:31 +1000 [thread overview]
Message-ID: <20100817045331.GE24726@drongo> (raw)
In-Reply-To: <1282008846-11833-1-git-send-regression-fweisbec@gmail.com>
On Tue, Aug 17, 2010 at 03:34:06AM +0200, Frederic Weisbecker wrote:
> Now that software events don't have interrupt disabled anymore in
> the event path, callchains can nest on any context. So seperating
> nmi and others contexts in two buffers has become racy.
>
> Fix this by providing one buffer per nesting level. Given the size
> of the callchain entries (2040 bytes * 4), we now need to allocate
> them dynamically.
>
> v2: Fixed put_callchain_entry call after recursion.
> Fix the type of the recursion, it must be an array.
>
> v3: Use a manual pr cpu allocation (temporary solution until NMIs
> can safely access vmalloc'ed memory).
It would be nice to make these allocations node-local.
Also, I see that we're allocating 4 buffers per cpu on powerpc when we
strictly only need 3, but I don't suppose that really matters.
Paul.
next prev parent reply other threads:[~2010-08-17 4:53 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-16 20:48 [RFC PATCH 0/0 v3] callchain fixes and cleanups Frederic Weisbecker
2010-08-16 20:48 ` [RFC PATCH 1/6] perf: Drop unappropriate tests on arch callchains Frederic Weisbecker
2010-08-16 20:48 ` [RFC PATCH 2/6] perf: Generalize callchain_store() Frederic Weisbecker
2010-08-17 4:37 ` Paul Mackerras
2010-08-16 20:48 ` [RFC PATCH 3/6] perf: Generalize some arch callchain code Frederic Weisbecker
2010-08-17 3:46 ` Paul Mackerras
2010-08-18 3:51 ` Frederic Weisbecker
2010-08-16 20:48 ` [RFC PATCH 4/6] perf: Factorize callchain context handling Frederic Weisbecker
2010-08-17 4:37 ` Paul Mackerras
2010-08-16 20:48 ` [RFC PATCH 5/6] perf: Fix race in callchains Frederic Weisbecker
2010-08-17 1:34 ` [RFC PATCH 5/6 v4] " Frederic Weisbecker
2010-08-17 4:53 ` Paul Mackerras [this message]
2010-08-18 3:49 ` Frederic Weisbecker
2010-08-16 20:48 ` [RFC PATCH 6/6] perf: Humanize the number of contexts Frederic Weisbecker
2010-08-17 4:58 ` [RFC PATCH 0/0 v3] callchain fixes and cleanups Borislav Petkov
2010-08-18 3:53 ` Frederic Weisbecker
2010-08-17 10:32 ` Will Deacon
2010-08-18 3:55 ` Frederic Weisbecker
2010-08-18 9:08 ` Will Deacon
2010-08-18 16:15 ` Ingo Molnar
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