linux-kernel - [tip:perf/core] perf report: Documentation average IPC and IPC coverage

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Message-ID: <tip-239ca3e78609378a1ed5d9db1c7db629a71c2857@git.kernel.org>
Date:   Tue, 18 Dec 2018 06:00:38 -0800
From:   tip-bot for Jin Yao <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     hpa@...or.com, kan.liang@...ux.intel.com,
        alexander.shishkin@...ux.intel.com, linux-kernel@...r.kernel.org,
        peterz@...radead.org, jolsa@...nel.org, tglx@...utronix.de,
        mingo@...nel.org, acme@...hat.com, ak@...ux.intel.com,
        yao.jin@...ux.intel.com
Subject: [tip:perf/core] perf report: Documentation average IPC and IPC
 coverage

Commit-ID:  239ca3e78609378a1ed5d9db1c7db629a71c2857
Gitweb:     https://git.kernel.org/tip/239ca3e78609378a1ed5d9db1c7db629a71c2857
Author:     Jin Yao <yao.jin@...ux.intel.com>
AuthorDate: Fri, 30 Nov 2018 21:54:57 +0800
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Mon, 17 Dec 2018 14:55:49 -0300

perf report: Documentation average IPC and IPC coverage

Add explanations for new columns "IPC" and "IPC coverage" in perf
documentation.

 v5:
 ---
 Update the description according to Ingo's comments.

Signed-off-by: Jin Yao <yao.jin@...ux.intel.com>
Reviewed-by: Ingo Molnar <mingo@...nel.org>
Reviewed-by: Jiri Olsa <jolsa@...nel.org>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Kan Liang <kan.liang@...ux.intel.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Link: http://lkml.kernel.org/r/1543586097-27632-5-git-send-email-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/Documentation/perf-report.txt | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index 474a4941f65d..ed2bf37ab132 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -126,6 +126,14 @@ OPTIONS
 	And default sort keys are changed to comm, dso_from, symbol_from, dso_to
 	and symbol_to, see '--branch-stack'.
 
+	When the sort key symbol is specified, columns "IPC" and "IPC Coverage"
+	are enabled automatically. Column "IPC" reports the average IPC per function
+	and column "IPC coverage" reports the percentage of instructions with
+	sampled IPC in this function. IPC means Instruction Per Cycle. If it's low,
+	it indicates there may be a performance bottleneck when the function is
+	executed, such as a memory access bottleneck. If a function has high overhead
+	and low IPC, it's worth further analyzing it to optimize its performance.
+
 	If the --mem-mode option is used, the following sort keys are also available
 	(incompatible with --branch-stack):
 	symbol_daddr, dso_daddr, locked, tlb, mem, snoop, dcacheline.