From 0dfbe4c646bf06a85c3d70572a8b8aa6ebffe3d5 Mon Sep 17 00:00:00 2001 From: Jin Yao Date: Fri, 23 Oct 2020 08:53:34 +0800 Subject: [PATCH] perf vendor events: Fix DRAM_BW_Use 0 issue for CLX/SKX Ian reports an issue that the metric DRAM_BW_Use often remains 0. The metric expression for DRAM_BW_Use on CLX/SKX: "( 64 * ( uncore_imc@cas_count_read@ + uncore_imc@cas_count_write@ ) / 1000000000 ) / duration_time" The counts of uncore_imc/cas_count_read/ and uncore_imc/cas_count_write/ are scaled up by 64, that is to turn a count of cache lines into bytes, the count is then divided by 1000000000 to give GB. However, the counts of uncore_imc/cas_count_read/ and uncore_imc/cas_count_write/ have been scaled yet. The scale values are from sysfs, such as /sys/devices/uncore_imc_0/events/cas_count_read.scale. It's 6.103515625e-5 (64 / 1024.0 / 1024.0). So if we use original metric expression, the result is not correct. But the difficulty is, for SKL client, the counts are not scaled. The metric expression for DRAM_BW_Use on SKL: "64 * ( arb@event\\=0x81\\,umask\\=0x1@ + arb@event\\=0x84\\,umask\\=0x1@ ) / 1000000 / duration_time / 1000" root@kbl-ppc:~# perf stat -M DRAM_BW_Use -a -- sleep 1 Performance counter stats for 'system wide': 190 arb/event=0x84,umask=0x1/ # 1.86 DRAM_BW_Use 29,093,178 arb/event=0x81,umask=0x1/ 1,000,703,287 ns duration_time 1.000703287 seconds time elapsed The result is expected. So the easy way is just change the metric expression for CLX/SKX. This patch changes the metric expression to: "( ( ( uncore_imc@cas_count_read@ + uncore_imc@cas_count_write@ ) * 1048576 ) / 1000000000 ) / duration_time" 1048576 = 1024 * 1024. Before (tested on CLX): root@lkp-csl-2sp5 ~# perf stat -M DRAM_BW_Use -a -- sleep 1 Performance counter stats for 'system wide': 765.35 MiB uncore_imc/cas_count_read/ # 0.00 DRAM_BW_Use 5.42 MiB uncore_imc/cas_count_write/ 1001515088 ns duration_time 1.001515088 seconds time elapsed After: root@lkp-csl-2sp5 ~# perf stat -M DRAM_BW_Use -a -- sleep 1 Performance counter stats for 'system wide': 767.95 MiB uncore_imc/cas_count_read/ # 0.80 DRAM_BW_Use 5.02 MiB uncore_imc/cas_count_write/ 1001900010 ns duration_time 1.001900010 seconds time elapsed Fixes: 038d3b53c284 ("perf vendor events intel: Update CascadelakeX events to v1.08") Fixes: b5ff7f2799a4 ("perf vendor events: Update SkylakeX events to v1.21") Signed-off-by: Jin Yao Acked-by: Ian Rogers Cc: Alexander Shishkin Cc: Andi Kleen Cc: Jiri Olsa Cc: Kan Liang Cc: Peter Zijlstra Link: http://lore.kernel.org/lkml/20201023005334.7869-1-yao.jin@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/pmu-events/arch/x86/cascadelakex/clx-metrics.json | 2 +- tools/perf/pmu-events/arch/x86/skylakex/skx-metrics.json | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/perf/pmu-events/arch/x86/cascadelakex/clx-metrics.json b/tools/perf/pmu-events/arch/x86/cascadelakex/clx-metrics.json index de3193552277..00f4fcffa815 100644 --- a/tools/perf/pmu-events/arch/x86/cascadelakex/clx-metrics.json +++ b/tools/perf/pmu-events/arch/x86/cascadelakex/clx-metrics.json @@ -329,7 +329,7 @@ }, { "BriefDescription": "Average external Memory Bandwidth Use for reads and writes [GB / sec]", - "MetricExpr": "( 64 * ( uncore_imc@cas_count_read@ + uncore_imc@cas_count_write@ ) / 1000000000 ) / duration_time", + "MetricExpr": "( ( ( uncore_imc@cas_count_read@ + uncore_imc@cas_count_write@ ) * 1048576 ) / 1000000000 ) / duration_time", "MetricGroup": "Memory_BW;SoC", "MetricName": "DRAM_BW_Use" }, diff --git a/tools/perf/pmu-events/arch/x86/skylakex/skx-metrics.json b/tools/perf/pmu-events/arch/x86/skylakex/skx-metrics.json index f31794d3b926..0dd8b13b5cfb 100644 --- a/tools/perf/pmu-events/arch/x86/skylakex/skx-metrics.json +++ b/tools/perf/pmu-events/arch/x86/skylakex/skx-metrics.json @@ -323,7 +323,7 @@ }, { "BriefDescription": "Average external Memory Bandwidth Use for reads and writes [GB / sec]", - "MetricExpr": "( 64 * ( uncore_imc@cas_count_read@ + uncore_imc@cas_count_write@ ) / 1000000000 ) / duration_time", + "MetricExpr": "( ( ( uncore_imc@cas_count_read@ + uncore_imc@cas_count_write@ ) * 1048576 ) / 1000000000 ) / duration_time", "MetricGroup": "Memory_BW;SoC", "MetricName": "DRAM_BW_Use" }, -- 2.34.1