From b63940970492f5f187d546e191bc2c6831491fe3 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Fri, 28 Feb 2014 06:02:14 -0800 Subject: [PATCH] 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 Cc: Stephane Eranian Link: http://lkml.kernel.org/r/1393596135-4227-2-git-send-email-andi@firstfloor.org Signed-off-by: Arnaldo Carvalho de Melo --- 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 888d51137fbe..1d78a4064da4 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 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 ------- ...::