From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnaldo Carvalho de Melo Subject: [PATCH 08/44] perf stat: Improve scaling Date: Thu, 21 Mar 2019 15:51:06 -0300 Message-ID: <20190321185142.11441-9-acme@kernel.org> References: <20190321185142.11441-1-acme@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190321185142.11441-1-acme@kernel.org> Sender: linux-kernel-owner@vger.kernel.org To: Ingo Molnar Cc: Jiri Olsa , Namhyung Kim , Clark Williams , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Andi Kleen , Arnaldo Carvalho de Melo List-Id: linux-perf-users.vger.kernel.org From: Andi Kleen The multiplexing scaling in perf stat mysteriously adds 0.5 to the value. This dates back to the original perf tool. Other scaling code doesn't use that strange convention. Remove the extra 0.5. Before: $ perf stat -e 'cycles,cycles,cycles,cycles,cycles,cycles' grep -rq foo Performance counter stats for 'grep -rq foo': 6,403,580 cycles (81.62%) 6,404,341 cycles (81.64%) 6,402,983 cycles (81.62%) 6,399,941 cycles (81.63%) 6,399,451 cycles (81.62%) 6,436,105 cycles (91.87%) 0.005843799 seconds time elapsed 0.002905000 seconds user 0.002902000 seconds sys After: $ perf stat -e 'cycles,cycles,cycles,cycles,cycles,cycles' grep -rq foo Performance counter stats for 'grep -rq foo': 6,422,704 cycles (81.68%) 6,401,842 cycles (81.68%) 6,398,432 cycles (81.68%) 6,397,098 cycles (81.68%) 6,396,074 cycles (81.67%) 6,434,980 cycles (91.62%) 0.005884437 seconds time elapsed 0.003580000 seconds user 0.002356000 seconds sys Signed-off-by: Andi Kleen Acked-by: Jiri Olsa LPU-Reference: 20190314225002.30108-10-andi@firstfloor.org Tested-by: Arnaldo Carvalho de Melo Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/evsel.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 53ec40cacd4b..16f02b83b23f 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -1342,7 +1342,7 @@ void perf_counts_values__scale(struct perf_counts_values *count, count->val = 0; } else if (count->run < count->ena) { scaled = 1; - count->val = (u64)((double) count->val * count->ena / count->run + 0.5); + count->val = (u64)((double) count->val * count->ena / count->run); } } -- 2.20.1