From: Adrian Hunter <adrian.hunter@intel.com>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>, Andi Kleen <ak@linux.intel.com>,
Alexey Budankov <alexey.budankov@linux.intel.com>,
Namhyung Kim <namhyung@kernel.org>,
linux-kernel@vger.kernel.org
Subject: [PATCH V2 6/6] perf intel-pt: Document snapshot control command
Date: Tue, 1 Sep 2020 12:37:58 +0300 [thread overview]
Message-ID: <20200901093758.32293-7-adrian.hunter@intel.com> (raw)
In-Reply-To: <20200901093758.32293-1-adrian.hunter@intel.com>
The documentation descibes snapshot mode. Update it to include the new
snapshot control command.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
tools/perf/Documentation/perf-intel-pt.txt | 23 +++++++++++++++++++---
1 file changed, 20 insertions(+), 3 deletions(-)
diff --git a/tools/perf/Documentation/perf-intel-pt.txt b/tools/perf/Documentation/perf-intel-pt.txt
index d5a266d7f15b..cb637e0d0743 100644
--- a/tools/perf/Documentation/perf-intel-pt.txt
+++ b/tools/perf/Documentation/perf-intel-pt.txt
@@ -558,7 +558,7 @@ The mmap size and auxtrace mmap size are displayed if the -vv option is used e.g
Intel PT modes of operation
~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Intel PT can be used in 2 modes:
+Intel PT can be used in 3 modes:
full-trace mode
sample mode
snapshot mode
@@ -571,7 +571,8 @@ Sample mode attaches a Intel PT sample to other events e.g.
perf record --aux-sample -e intel_pt//u -e branch-misses:u
-Snapshot mode captures the available data when a signal is sent e.g.
+Snapshot mode captures the available data when a signal is sent or "snapshot"
+control command is issued. e.g. using a signal
perf record -v -e intel_pt//u -S ./loopy 1000000000 &
[1] 11435
@@ -582,7 +583,23 @@ Note that the signal sent is SIGUSR2.
Note that "Recording AUX area tracing snapshot" is displayed because the -v
option is used.
-The 2 modes cannot be used together.
+The advantage of using "snapshot" control command is that the access is
+controlled by access to a FIFO e.g.
+
+ $ mkfifo perf.control
+ $ mkfifo perf.ack
+ $ cat perf.ack &
+ [1] 15235
+ $ sudo ~/bin/perf record --control fifo:perf.control,perf.ack -S -e intel_pt//u -- sleep 60 &
+ [2] 15243
+ $ ps -e | grep perf
+ 15244 pts/1 00:00:00 perf
+ $ kill -USR2 15244
+ bash: kill: (15244) - Operation not permitted
+ $ echo snapshot > perf.control
+ ack
+
+The 3 Intel PT modes of operation cannot be used together.
Buffer handling
--
2.17.1
next prev parent reply other threads:[~2020-09-01 9:38 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-01 9:37 [PATCH V2 0/6] perf tools: Enable AUX area tracing snapshots using a FIFO Adrian Hunter
2020-09-01 9:37 ` [PATCH V2 1/6] perf tools: Consolidate --control option parsing into one function Adrian Hunter
2020-09-02 16:06 ` Alexey Budankov
2020-09-03 20:15 ` Arnaldo Carvalho de Melo
2020-09-01 9:37 ` [PATCH V2 2/6] perf tools: Handle read errors from ctl_fd Adrian Hunter
2020-09-02 16:11 ` Alexey Budankov
2020-09-03 20:16 ` Arnaldo Carvalho de Melo
2020-09-01 9:37 ` [PATCH V2 3/6] perf tools: Use AsciiDoc formatting for --control option documentation Adrian Hunter
2020-09-02 16:12 ` Alexey Budankov
2020-09-03 20:17 ` Arnaldo Carvalho de Melo
2020-09-01 9:37 ` [PATCH V2 4/6] perf tools: Add FIFO file names as alternative options to --control Adrian Hunter
2020-09-01 20:06 ` Jiri Olsa
2020-09-02 10:57 ` [PATCH V3 " Adrian Hunter
2020-09-02 17:03 ` Alexey Budankov
2020-09-03 10:38 ` Adrian Hunter
2020-09-03 12:29 ` [PATCH] perf tools: Consolidate close_control_option()'s into one function Adrian Hunter
2020-09-04 18:56 ` Arnaldo Carvalho de Melo
2020-09-03 20:21 ` [PATCH V3 4/6] perf tools: Add FIFO file names as alternative options to --control Arnaldo Carvalho de Melo
2020-09-01 9:37 ` [PATCH V2 5/6] perf record: Add 'snapshot' control command Adrian Hunter
2020-09-02 17:03 ` Alexey Budankov
2020-09-03 10:44 ` Adrian Hunter
2020-09-01 9:37 ` Adrian Hunter [this message]
2020-09-02 16:53 ` [PATCH V2 6/6] perf intel-pt: Document snapshot " Alexey Budankov
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