From 9dc9a95f03a69ab926d9ff1986ab2087f34a5dce Mon Sep 17 00:00:00 2001 From: Alexey Budankov Date: Tue, 3 Apr 2018 21:18:33 +0300 Subject: perf stat: Enable 1ms interval for printing event counters values Currently print count interval for performance counters values is limited by 10ms so reading the values at frequencies higher than 100Hz is restricted by the tool. This change makes perf stat -I possible on frequencies up to 1KHz and, to some extent, makes perf stat -I to be on-par with perf record sampling profiling. When running perf stat -I for monitoring e.g. PCIe uncore counters and at the same time profiling some I/O workload by perf record e.g. for cpu-cycles and context switches, it is then possible to observe consolidated CPU/OS/IO(Uncore) performance picture for that workload. Tool overhead warning printed when specifying -v option can be missed due to screen scrolling in case you have output to the console so message is moved into help available by running perf stat -h. Signed-off-by: Alexey Budankov Acked-by: Jiri Olsa Cc: Alexander Shishkin Cc: Andi Kleen Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/b842ad6a-d606-32e4-afe5-974071b5198e@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/Documentation/perf-stat.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools/perf/Documentation') diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt index f15b306be183..e6c3b4e555c2 100644 --- a/tools/perf/Documentation/perf-stat.txt +++ b/tools/perf/Documentation/perf-stat.txt @@ -153,7 +153,7 @@ perf stat --repeat 10 --null --sync --pre 'make -s O=defconfig-build/clean' -- m -I msecs:: --interval-print msecs:: -Print count deltas every N milliseconds (minimum: 10ms) +Print count deltas every N milliseconds (minimum: 1ms) The overhead percentage could be high in some cases, for instance with small, sub 100ms intervals. Use with caution. example: 'perf stat -I 1000 -e cycles -a sleep 5' -- cgit v1.2.3