From: Peter Zijlstra <peterz@infradead.org>
To: David Rientjes <rientjes@google.com>
Cc: Paul Mackerras <paulus@samba.org>, Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Stephane Eranian <eranian@google.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [patch] x86, perf: avoid spamming kernel log for bts buffer failure
Date: Tue, 1 Jul 2014 11:34:42 +0200 [thread overview]
Message-ID: <20140701093442.GN6758@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <alpine.DEB.2.02.1406301600460.26302@chino.kir.corp.google.com>
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On Mon, Jun 30, 2014 at 04:04:08PM -0700, David Rientjes wrote:
> It's unnecessary to excessively spam the kernel log anytime the BTS buffer
> cannot be allocated, so make this allocation __GFP_NOWARN.
>
> The user probably will want to at least find some artifact that the
> allocation has failed in the past, probably due to fragmentation because
> of its large size, when it's not allocated at bootstrap. Thus, add a
> WARN_ONCE() so something is left behind for them to understand why perf
> commnads that require PEBS is not working properly.
Can you elaborate a bit under which conditions this triggered? Typically
we should be doing fairly well allocating such buffers with GFP_KERNEL,
that should allow things like compaction to run and create higher order
pages.
And the BTS (branch trace store) isn't _that_ large.
That said, the patch is reasonable; although arguably we should maybe do
the same to alloc_pebs_buffer().
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next prev parent reply other threads:[~2014-07-01 9:34 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-30 23:04 [patch] x86, perf: avoid spamming kernel log for bts buffer failure David Rientjes
2014-07-01 9:34 ` Peter Zijlstra [this message]
2014-07-02 13:16 ` Stephane Eranian
2014-07-02 13:31 ` Peter Zijlstra
2014-07-02 13:38 ` Stephane Eranian
2014-07-02 14:54 ` Peter Zijlstra
2014-07-02 23:30 ` David Rientjes
2014-07-14 23:33 ` David Rientjes
2014-07-15 8:53 ` Peter Zijlstra
2014-07-16 19:21 ` [tip:perf/urgent] perf/x86/intel: Avoid spamming kernel log for BTS " tip-bot for David Rientjes
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