From: Andi Kleen <ak@linux.intel.com>
To: Stephane Eranian <eranian@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Kan Liang <kan.liang@intel.com>,
LKML <linux-kernel@vger.kernel.org>,
"mingo@redhat.com" <mingo@redhat.com>,
Paul Mackerras <paulus@samba.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Jiri Olsa <jolsa@redhat.com>
Subject: Re: [PATCH V7 13/17] perf, x86: enable LBR callstack when recording callchain
Date: Wed, 5 Nov 2014 09:40:31 -0800 [thread overview]
Message-ID: <20141105174031.GO3274@tassilo.jf.intel.com> (raw)
In-Reply-To: <CABPqkBS89jrjOMR9b_7WudJ0rDn0uD8XxX2gCJYDvTEssjXcww@mail.gmail.com>
> The reason why using LBR call stack mode is restricted to user level
> only is because of
> a bug in the LBR call stack hardware which forces the kernel to drop
> LBR_FREEZE_PMI.
It works with PEBS events, just not with non PEBS (the patch currently
does not implement this distinction and I'm not sure it's worth it)
> In other words ,the LBR does not stop on counter overflow, thus it
> will be wiped out by
> execution of kernel code leading to the PMU interrupt handler.
It stops, but it takes some time to stop so the call-return stack
can get out of sync.
-Andi
--
ak@linux.intel.com -- Speaking for myself only
next prev parent reply other threads:[~2014-11-05 17:40 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-05 2:55 [PATCH V7 00/17] perf, x86: Haswell LBR call stack support Kan Liang
2014-11-05 2:55 ` [PATCH V7 01/17] perf, x86: Reduce lbr_sel_map size Kan Liang
2015-02-18 17:13 ` [tip:perf/core] perf/x86/intel: Reduce lbr_sel_map[] size tip-bot for Yan, Zheng
2014-11-05 2:55 ` [PATCH V7 02/17] perf, core: introduce pmu context switch callback Kan Liang
2015-02-18 17:14 ` [tip:perf/core] perf: Introduce " tip-bot for Yan, Zheng
2014-11-05 2:55 ` [PATCH V7 03/17] perf, x86: use context switch callback to flush LBR stack Kan Liang
2015-02-18 17:14 ` [tip:perf/core] perf/x86/intel: Use " tip-bot for Yan, Zheng
2014-11-05 2:56 ` [PATCH V7 04/17] perf, x86: Basic Haswell LBR call stack support Kan Liang
2015-02-18 17:14 ` [tip:perf/core] perf/x86/intel: Add basic " tip-bot for Yan, Zheng
2014-11-05 2:56 ` [PATCH V7 05/17] perf, core: pmu specific data for perf task context Kan Liang
2015-02-18 17:15 ` [tip:perf/core] perf: Add " tip-bot for Yan, Zheng
2015-12-09 8:34 ` Peter Zijlstra
2015-12-09 14:59 ` Liang, Kan
2015-12-09 15:14 ` Peter Zijlstra
2015-12-09 15:25 ` Liang, Kan
2014-11-05 2:56 ` [PATCH V7 06/17] perf, core: always switch pmu specific data during context switch Kan Liang
2015-02-18 17:15 ` [tip:perf/core] perf: Always " tip-bot for Yan, Zheng
2014-11-05 2:56 ` [PATCH V7 07/17] perf, x86: allocate space for storing LBR stack Kan Liang
2015-02-18 17:15 ` [tip:perf/core] perf/x86/intel: Allocate " tip-bot for Yan, Zheng
2014-11-05 2:56 ` [PATCH V7 08/17] perf, x86: track number of events that use LBR callstack Kan Liang
2015-02-18 17:15 ` [tip:perf/core] perf/x86/intel: Track number of events that use the " tip-bot for Yan, Zheng
2014-11-05 2:56 ` [PATCH V7 09/17] perf, x86: Save/resotre LBR stack during context switch Kan Liang
2015-02-18 17:16 ` [tip:perf/core] perf/x86/intel: Save/ restore " tip-bot for Yan, Zheng
2014-11-05 2:56 ` [PATCH V7 10/17] perf, core: simplify need branch stack check Kan Liang
2015-02-18 17:16 ` [tip:perf/core] perf: Simplify the " tip-bot for Yan, Zheng
2014-11-05 2:56 ` [PATCH V7 11/17] perf, core: expose LBR call stack to user perf tool Kan Liang
2014-11-05 9:20 ` Peter Zijlstra
2014-11-05 2:56 ` [PATCH V7 12/17] perf, x86: re-organize code that implicitly enables LBR/PEBS Kan Liang
2015-02-18 17:16 ` [tip:perf/core] perf/x86/intel: Re-organize " tip-bot for Yan, Zheng
2014-11-05 2:56 ` [PATCH V7 13/17] perf, x86: enable LBR callstack when recording callchain Kan Liang
2014-11-05 9:21 ` Peter Zijlstra
2014-11-05 9:58 ` Stephane Eranian
2014-11-05 10:43 ` Peter Zijlstra
2014-11-05 10:57 ` Stephane Eranian
2014-11-05 12:49 ` Peter Zijlstra
2014-11-05 13:22 ` Stephane Eranian
2014-11-05 15:45 ` Peter Zijlstra
2014-11-05 15:53 ` Liang, Kan
2014-11-05 16:29 ` Peter Zijlstra
2014-11-05 17:52 ` Andi Kleen
2014-11-05 17:57 ` Andi Kleen
2014-11-05 17:40 ` Andi Kleen [this message]
2014-11-05 2:56 ` [PATCH V7 14/17] perf, x86: disable FREEZE_LBRS_ON_PMI when LBR operates in callstack mode Kan Liang
2015-02-18 17:17 ` [tip:perf/core] perf/x86/intel: Disable " tip-bot for Yan, Zheng
2014-11-05 2:56 ` [PATCH V7 15/17] perf, x86: Discard zero length call entries in LBR call stack Kan Liang
2015-02-18 17:17 ` [tip:perf/core] perf/x86/intel: " tip-bot for Yan, Zheng
2014-11-05 2:56 ` [PATCH V7 16/17] perf tools: handle LBR call stack data Kan Liang
2014-11-05 2:56 ` [PATCH V7 17/17] perf tools: choose to dump callchain from LBR and FP Kan Liang
2014-11-05 9:37 ` [PATCH V7 00/17] perf, x86: Haswell LBR call stack support Peter Zijlstra
2014-11-05 16:22 ` Liang, Kan
2014-11-05 16:27 ` Peter Zijlstra
2014-11-05 17:02 ` Liang, Kan
2015-02-18 17:17 ` [tip:perf/core] perf/x86/intel: Expose LBR callstack to user space tooling tip-bot for Peter Zijlstra
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