From: Stephane Eranian <eranian@google.com>
To: linux-kernel@vger.kernel.org
Cc: acme@redhat.com, peterz@infradead.org, mingo@elte.hu,
ak@linux.intel.com, kan.liang@intel.com, jolsa@redhat.com
Subject: [PATCH v4 4/5] perf/record: add documentation for using PERF_SAMPLE_SKID_IP
Date: Wed, 8 Nov 2017 23:57:12 -0800 [thread overview]
Message-ID: <1510214233-2074-5-git-send-email-eranian@google.com> (raw)
In-Reply-To: <1510214233-2074-1-git-send-email-eranian@google.com>
This patch adds documentation to describe how to use the skid
ip support with perf record. The sample type can be provided
per event as follows: pmu_instance/...,skid-ip=1/
For instance on Intel X86:
$ perf record -e cpu/event=0xc5,skid-ip=1/pp
does record the precise address of retired branches and their target.
Signed-off-by: Stephane Eranian <eranian@google.com>
---
tools/perf/Documentation/perf-record.txt | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 5a626ef666c2..f0e3636dc4be 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -57,6 +57,14 @@ OPTIONS
FP mode, "dwarf" for DWARF mode, "lbr" for LBR mode and
"no" for disable callgraph.
- 'stack-size': user stack size for dwarf mode
+ - 'skid-ip' : boolean, captures the unmodified interrupt instruction pointer
+ (IP) in each sample. Usually with event-based sampling, the IP
+ has skid and rarely point to the instruction which caused the
+ event to overflow. On some architectures, the hardware can eliminate
+ the skid and perf_events returns it as the IP with precise sampling is
+ enabled. But for certain measurements, it may be useful to have both
+ the correct and skid ip. This option enable capturing the skid ip in
+ additional to the corrected ip. Default is: false
See the linkperf:perf-list[1] man page for more parameters.
--
2.7.4
next prev parent reply other threads:[~2017-11-09 7:58 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-09 7:57 [PATCH v4 0/5] perf: add support for capturing skid IP Stephane Eranian
2017-11-09 7:57 ` [PATCH v4 1/5] perf/core: add PERF_RECORD_SAMPLE_SKID_IP record type Stephane Eranian
2017-11-09 7:57 ` [PATCH v4 2/5] perf/x86: add PERF_SAMPLE_SKID_IP support for X86 PEBS Stephane Eranian
2017-11-09 7:57 ` [PATCH v4 3/5] perf/tools: add support for PERF_SAMPLE_SKID_IP Stephane Eranian
2017-11-09 7:57 ` Stephane Eranian [this message]
2017-11-09 7:57 ` [PATCH v4 5/5] perf/script: " Stephane Eranian
2017-11-13 11:52 ` Jiri Olsa
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