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 09:57:03 -0800 [thread overview]
Message-ID: <20141105175703.GQ3274@tassilo.jf.intel.com> (raw)
In-Reply-To: <CABPqkBRF6VEigBcBr+6Hy5E3tmfk4vpDiR8Zui8=853GTjG_XQ@mail.gmail.com>
> LBR callstack fails for leaf function optimization. Where the callee does
> not return to its caller but instead to the caller's caller. That is the one
> case I know about. There are others I believe.
No it should work fine for this case. You just don't see the tail call,
but the call stack does not get out of sync, so future calls work fine.
It's the same as with frame pointers or even dwarf.
Typical cases that throw it off are throwing exceptions or user space
context switching.
One somewhat common case that used to throw it off was the
call 1f ; 1: pop %ebx
older 32bit binaries used to do to get the PIC offset. That has been
fixed in newer compilers by using an out of line function
(and also Broadwell has a workaround for this)
-Andi
--
ak@linux.intel.com -- Speaking for myself only
next prev parent reply other threads:[~2014-11-05 17:57 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 [this message]
2014-11-05 17:40 ` Andi Kleen
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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