From: "Yan, Zheng" <zheng.z.yan@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
eranian@google.com, andi@firstfloor.org
Subject: Re: [PATCH v2 3/7] perf, x86: Introduce x86 special perf event context
Date: Mon, 08 Jul 2013 16:51:03 +0800 [thread overview]
Message-ID: <51DA7D77.3000806@intel.com> (raw)
In-Reply-To: <20130705124500.GS23916@twins.programming.kicks-ass.net>
On 07/05/2013 08:45 PM, Peter Zijlstra wrote:
> On Fri, Jul 05, 2013 at 11:19:31AM +0800, Yan, Zheng wrote:
>> On 07/04/2013 08:41 PM, Peter Zijlstra wrote:
>>> It should be *optional*, also wtf is that parent_ctx thing for?
>>
>> parent_ctx is for the fork() case, used for checking if the callstack feature
>> is enabled for the parent task. If yes, clone parent task's LBR stack.
>> For the simple program below:
>
> So there's a problem with all this; contexts aren't strict per task, we
> play games with them in perf_event_context_sched_out(). We'd have to
> disable that context switch optimization for LBR stack to work and
> that's massively expensive.
>
Sorry, I didn't realize the optimization. I will describe my change in more details
in the further.
Yan, Zheng
> If you actually did that, you again fail for not having mentioned this
> in your changelog.
>
> I'm starting to not want to read patches from you; going through them is
> just too much effort, I might as well write the stuff myself :/
>
next prev parent reply other threads:[~2013-07-08 8:51 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-01 7:23 [PATCH v2 0/7] perf, x86: Haswell LBR call stack support Yan, Zheng
2013-07-01 7:23 ` [PATCH v2 1/7] perf, x86: Reduce lbr_sel_map size Yan, Zheng
2013-07-01 7:23 ` [PATCH v2 2/7] perf, x86: Basic Haswell LBR call stack support Yan, Zheng
2013-07-01 7:23 ` [PATCH v2 3/7] perf, x86: Introduce x86 special perf event context Yan, Zheng
2013-07-04 12:41 ` Peter Zijlstra
2013-07-05 3:19 ` Yan, Zheng
2013-07-05 12:45 ` Peter Zijlstra
2013-07-08 8:51 ` Yan, Zheng [this message]
2013-07-01 7:23 ` [PATCH v2 4/7] perf, x86: Save/resotre LBR stack during context switch Yan, Zheng
2013-07-04 9:57 ` Peter Zijlstra
2013-07-04 11:39 ` Yan, Zheng
2013-07-04 13:44 ` Andi Kleen
2013-07-04 14:00 ` Peter Zijlstra
2013-07-10 17:57 ` Andi Kleen
2013-07-04 12:44 ` Peter Zijlstra
2013-07-04 12:45 ` Peter Zijlstra
2013-07-05 5:36 ` Yan, Zheng
2013-07-05 8:15 ` Peter Zijlstra
2013-07-05 8:51 ` Yan, Zheng
2013-07-05 12:31 ` Peter Zijlstra
2013-08-08 6:18 ` Yan, Zheng
2013-07-01 7:23 ` [PATCH v2 5/7] perf, core: Pass perf_sample_data to perf_callchain() Yan, Zheng
2013-07-01 7:23 ` [PATCH v2 6/7] perf, x86: Use LBR call stack to get user callchain Yan, Zheng
2013-07-01 7:23 ` [PATCH v2 7/7] perf, x86: Discard zero length call entries in LBR call stack Yan, Zheng
-- strict thread matches above, loose matches on Subject: below --
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 3/7] perf, x86: Introduce x86 special perf event context Yan, Zheng
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