From: "Yan, Zheng" <zheng.z.yan@intel.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, a.p.zijlstra@chello.nl, eranian@google.com,
andi@firstfloor.org, "Yan, Zheng" <zheng.z.yan@intel.com>
Subject: [PATCH V3 0/7] perf, x86: Haswell LBR call stack support
Date: Mon, 25 Feb 2013 10:01:20 +0800 [thread overview]
Message-ID: <1361757687-5415-1-git-send-email-zheng.z.yan@intel.com> (raw)
From: "Yan, Zheng" <zheng.z.yan@intel.com>
Haswell has a new feature that utilizes the existing Last Branch Record
facility to record call chains. When the feature is enabled, function
call will be collected as normal, but as return instructions are executed
the last captured branch record is popped from the on-chip LBR registers.
The LBR call stack facility can help perf to get call chains of progam
without frame pointer. When perf tool requests PERF_SAMPLE_CALLCHAIN +
PERF_SAMPLE_BRANCH_USER, this feature is dynamically enabled by default.
This feature can be disabled/enabled through an attribute file in the cpu
pmu sysfs directory.
The LBR call stack has following known limitations
1. Zero length calls are not filtered out by hardware
2. Exception handing such as setjmp/longjmp will have calls/returns not
match
3. Pushing different return address onto the stack will have calls/returns
not match
These patches are based upon Andi's linux-misc hsw/pmu5
Available from
https://github.com/ukernel/linux.git hws/pmu5
Regards
Yan, Zheng
---
Changes since v1
- not expose PERF_SAMPLE_BRANCH_CALL_STACK to user space
- save/restore LBR stack on context switch for all sampling branch modes
- reduce lbr_sel_map size
Changes since v2
- only enable LBR call stack when user requests sampling user callchain
next reply other threads:[~2013-02-25 2:02 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-25 2:01 Yan, Zheng [this message]
2013-02-25 2:01 ` [PATCH 1/7] perf, x86: Reduce lbr_sel_map size Yan, Zheng
2013-02-25 2:01 ` [PATCH 2/7] perf, x86: Basic Haswell LBR call stack support Yan, Zheng
2013-02-25 2:01 ` [PATCH 3/7] perf, x86: Introduce x86 special perf event context Yan, Zheng
2013-02-25 2:01 ` [PATCH 4/7] perf, x86: Save/resotre LBR stack during context switch Yan, Zheng
2013-02-25 2:01 ` [PATCH 5/7] perf, core: Pass perf_sample_data to perf_callchain() Yan, Zheng
2013-02-25 2:01 ` [PATCH 6/7] perf, x86: Use LBR call stack to get user callchain Yan, Zheng
2013-02-25 2:01 ` [PATCH 7/7] perf, x86: Discard zero length call entries in LBR call stack Yan, Zheng
-- strict thread matches above, loose matches on Subject: below --
2012-11-06 6:38 [PATCH V3 0/7] perf, x86: Haswell LBR call stack support Yan, Zheng
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