Re: [PATCH v4 4/4] perf report: Documentation average IPC and IPC coverage

From: Jin, Yao
Date: Thu Nov 29 2018 - 19:22:59 EST

On 11/29/2018 9:27 PM, Ingo Molnar wrote:

* Jin Yao <yao.jin@xxxxxxxxxxxxxxx> wrote:

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

Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
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 474a494..e5a32f3 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 performance bottleneck when the function is
+ executed, such as, memory access bottleneck. If a function has high overhead
+ and low IPC, it's worth further analysis for performance optimization.

Thank you for adding this!

Just a few small nits:

s/may be performance bottleneck
/may be a performance bottleneck

s/such as, memory access bottleneck
/such as a memory access bottleneck

s/it's worth further analysis for performance optimization.
/it's worth further analyzing it to optimize its performance.


Other than that:

Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>


Thanks Ingo!

I will add these fixes in v5.

Jin Yao