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- "Yan, Zheng"
- "Yan, Zheng"
- "Yan, Zheng"
- "Yan, Zheng"
- "Yan, Zheng"
- "Yan, Zheng"
- "Yan, Zheng"
- "Yan, Zheng"
- "Yan, Zheng"
- "Yan, Zheng"
- "Yan, Zheng"
- "Yan, Zheng"
- "Yan, Zheng"
- "Yan, Zheng"
- "Yan, Zheng"
- "Yan, Zheng"
| | | From | "Yan, Zheng" <> | Subject | [PATCH 00/15] perf, x86: Haswell LBR call stack support | Date | Wed, 11 Dec 2013 15:10:45 +0800 |
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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. This feature can be disabled/enabled through an attribute file in the cpu pmu sysfs directory.
The LBR call stack has following known limitations - Zero length calls are not filtered out by hardware - Exception handing such as setjmp/longjmp will have calls/returns not match - Pushing different return address onto the stack will have calls/returns not match - If callstack is deeper than the LBR, only the last entries are captured
Change since previous version - split change into more patches - introduce context switch callback and use it to flush LBR - use the context switch callback to save/restore LBR - dynamic allocate memory area for storing LBR stack, always switch the memory area during context switch - disable this feature by default
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