From: Andi Kleen <ak@linux.intel.com>
To: Stephane Eranian <eranian@google.com>
Cc: "Yan, Zheng" <zheng.z.yan@intel.com>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH V2 6/7] perf, x86: Use LBR call stack to get user callchain
Date: Wed, 24 Oct 2012 05:31:24 -0700 [thread overview]
Message-ID: <20121024123124.GU2095@tassilo.jf.intel.com> (raw)
In-Reply-To: <CABPqkBQ+YMRvR6mv7NrW4-MZOgW6ztntJV5RMehr+SB9ymkYLw@mail.gmail.com>
On Wed, Oct 24, 2012 at 02:21:43PM +0200, Stephane Eranian wrote:
> But still, if I do:
> $ perf record -g -e cpu/cycles/k ........
>
> Looks like your code will activate LBR cstack for user stack even
> though I don't use it.
> I know it won't generate any user samples (theoretically) but you are
> still commandeering
> the LBR resource which other events may want to use.
You can disable it in sysfs. LBR is a power user feature and they will
know how to do this.
See it as a "prefer the needs of the 95+% over the needs of the few" default
-Andi
next prev parent reply other threads:[~2012-10-24 12:31 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-24 5:59 [PATCH V2 0/7] perf, x86: Haswell LBR call stack support Yan, Zheng
2012-10-24 5:59 ` [PATCH V2 1/7] perf, x86: Reduce lbr_sel_map size Yan, Zheng
2012-10-24 7:28 ` Stephane Eranian
2012-10-24 7:49 ` Yan, Zheng
2012-10-24 8:15 ` Stephane Eranian
2012-10-24 8:23 ` Yan, Zheng
2012-10-24 8:37 ` Yan, Zheng
2012-10-24 8:53 ` Stephane Eranian
2012-10-24 5:59 ` [PATCH V2 2/7] perf, x86: Basic Haswell LBR call stack support Yan, Zheng
2012-10-24 5:59 ` [PATCH V2 3/7] perf, x86: Introduce x86 special perf event context Yan, Zheng
2012-10-24 5:59 ` [PATCH V2 4/7] perf, x86: Save/resotre LBR stack during context switch Yan, Zheng
2012-10-24 5:59 ` [PATCH V2 5/7] perf, core: Pass perf_sample_data to perf_callchain() Yan, Zheng
2012-10-24 5:59 ` [PATCH V2 6/7] perf, x86: Use LBR call stack to get user callchain Yan, Zheng
2012-10-24 8:57 ` Stephane Eranian
2012-10-24 11:23 ` Yan, Zheng
2012-10-24 11:47 ` Stephane Eranian
2012-10-24 11:52 ` Yan, Zheng
2012-10-24 12:11 ` Stephane Eranian
2012-10-24 12:21 ` Stephane Eranian
2012-10-24 12:31 ` Andi Kleen [this message]
2012-10-24 12:36 ` Stephane Eranian
2012-10-24 12:41 ` Andi Kleen
2012-10-24 12:46 ` Yan, Zheng
2012-10-24 5:59 ` [PATCH V2 7/7] perf, x86: Discard zero length call entries in LBR call stack Yan, Zheng
2012-10-25 9:12 ` Namhyung Kim
2012-10-24 8:49 ` [PATCH V2 0/7] perf, x86: Haswell LBR call stack support Stephane Eranian
-- strict thread matches above, loose matches on Subject: below --
2013-07-01 7:23 [PATCH v2 " Yan, Zheng
2013-07-01 7:23 ` [PATCH v2 6/7] perf, x86: Use LBR call stack to get user callchain Yan, Zheng
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