From: Peter Zijlstra <peterz@infradead.org>
To: Stephane Eranian <eranian@google.com>
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, acme@redhat.com,
ming.m.lin@intel.com, andi@firstfloor.org,
robert.richter@amd.com, ravitillo@lbl.gov, will.deacon@arm.com,
paulus@samba.org, benh@kernel.crashing.org, rth@twiddle.net,
ralf@linux-mips.org, davem@davemloft.net, lethal@linux-sh.org
Subject: Re: [PATCH 07/12] perf_events: add LBR software filter support for Intel X86 (v2)
Date: Mon, 05 Dec 2011 23:29:40 +0100 [thread overview]
Message-ID: <1323124180.32012.45.camel@twins> (raw)
In-Reply-To: <1318595833-29984-8-git-send-email-eranian@google.com>
On Fri, 2011-10-14 at 14:37 +0200, Stephane Eranian wrote:
>
> This patch adds an internal sofware filter to complement
> the (optional) LBR hardware filter.
>
> The software filter is necessary:
> - as a substitute when there is no HW LBR filter (e.g., Atom, Core)
> - to complement HW LBR filter in case of errata (e.g., Nehalem/Westmere)
> - to provide finer grain filtering (e.g., all processors)
>
> Sometimes, the LBR HW filter cannot distinguish between two types
> of branches. For instance, to capture syscall as CALLS, it is necessary
> to enable the LBR_FAR filter which will also capture JMP instructions.
> Thus, a second pass is necessary to filter those out, this is what the
> SW filter can do.
>
> The SW filter is built on top of the internal x86 disassembler. It
> is a best effort filter especially for user level code. It is subject
> to the availability of the text page of the program.
>
> The SW filter is enabled on all Intel X86 processors. It is bypassed
> when the user is capturing all branches at all priv levels.
This patch is very seriously whitespace challenged.
next prev parent reply other threads:[~2011-12-05 22:30 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-14 12:37 [PATCH 00/12] perf_events: add support for sampling taken branches (v2) Stephane Eranian
2011-10-14 12:37 ` [PATCH 01/12] perf_events: add generic taken branch sampling support (v2) Stephane Eranian
2011-12-05 21:06 ` Peter Zijlstra
2011-12-06 19:42 ` Stephane Eranian
2011-12-05 22:14 ` Peter Zijlstra
2011-12-06 19:27 ` Stephane Eranian
2011-10-14 12:37 ` [PATCH 02/12] perf_events: add Intel LBR MSR definitions (v2) Stephane Eranian
2011-10-14 12:37 ` [PATCH 03/12] perf_events: add Intel X86 LBR sharing logic (v2) Stephane Eranian
2011-10-14 12:37 ` [PATCH 04/12] perf_events: sync branch stack sampling with X86 precise_sampling (v2) Stephane Eranian
2011-10-14 12:37 ` [PATCH 05/12] perf_events: add LBR mappings for PERF_SAMPLE_BRANCH filters (v2) Stephane Eranian
2011-12-05 22:35 ` Peter Zijlstra
2011-12-07 4:22 ` Stephane Eranian
2011-10-14 12:37 ` [PATCH 06/12] perf_events: implement PERF_SAMPLE_BRANCH for Intel X86 (v2) Stephane Eranian
2011-10-14 12:37 ` [PATCH 07/12] perf_events: add LBR software filter support " Stephane Eranian
2011-12-05 22:29 ` Peter Zijlstra [this message]
2011-10-14 12:37 ` [PATCH 08/12] perf_events: disable PERF_SAMPLE_BRANCH_* when not supported (v2) Stephane Eranian
2011-10-14 12:37 ` [PATCH 09/12] perf_events: add hook to flush branch_stack on context switch (v2) Stephane Eranian
2011-12-05 21:10 ` Peter Zijlstra
2011-12-05 21:37 ` Peter Zijlstra
2011-12-07 18:25 ` Stephane Eranian
2011-12-08 10:49 ` Peter Zijlstra
2011-12-08 18:04 ` Stephane Eranian
2011-12-08 18:13 ` Peter Zijlstra
2011-12-08 22:06 ` Stephane Eranian
2011-12-09 9:00 ` Peter Zijlstra
2011-10-14 12:37 ` [PATCH 10/12] perf: add code to support PERF_SAMPLE_BRANCH_STACK (v2) Stephane Eranian
2011-10-14 12:37 ` [PATCH 11/12] perf: add support for sampling taken branch to perf record (v2) Stephane Eranian
2011-10-14 12:37 ` [PATCH 12/12] perf: add support for taken branch sampling to perf report (v2) Stephane Eranian
2011-12-04 20:11 ` [PATCH 00/12] perf_events: add support for sampling taken branches (v2) Stephane Eranian
2011-12-05 15:27 ` Peter Zijlstra
2011-12-05 22:39 ` Peter Zijlstra
2011-12-06 9:49 ` Will Deacon
2011-12-06 11:03 ` Peter Zijlstra
2011-12-06 19:14 ` Stephane Eranian
2011-12-06 19:20 ` Peter Zijlstra
2011-12-06 19:22 ` Stephane Eranian
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