[tip:perf/core] perf mem: Clarify load-latency in documentation

[tip-bot for Andi Kleen]

Commit-ID:  b63940970492f5f187d546e191bc2c6831491fe3
Gitweb:     http://git.kernel.org/tip/b63940970492f5f187d546e191bc2c6831491fe3
Author:     Andi Kleen <ak@xxxxxxxxxxxxxxx>
AuthorDate: Fri, 28 Feb 2014 06:02:14 -0800
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Fri, 14 Mar 2014 11:20:44 -0300

perf mem: Clarify load-latency in documentation

Clarify in the documentation that 'perf mem report' reports use-latency,
not load/store-latency on Intel systems.

This often causes confusion with users.

Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1393596135-4227-2-git-send-email-andi@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/Documentation/perf-mem.txt | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/perf/Documentation/perf-mem.txt b/tools/perf/Documentation/perf-mem.txt
index 888d511..1d78a40 100644
--- a/tools/perf/Documentation/perf-mem.txt
+++ b/tools/perf/Documentation/perf-mem.txt
@@ -18,6 +18,10 @@ from it, into perf.data. Perf record options are accepted and are passed through
 "perf mem -t <TYPE> report" displays the result. It invokes perf report with the
 right set of options to display a memory access profile.
 
+Note that on Intel systems the memory latency reported is the use-latency,
+not the pure load (or store latency). Use latency includes any pipeline
+queueing delays in addition to the memory subsystem latency.
+
 OPTIONS
 -------
 <command>...::
--
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