From: Ian Rogers <irogers@google.com> To: "Liang, Kan" <kan.liang@linux.intel.com> Cc: Carel Si <beibei.si@intel.com>, acme@redhat.com, alexander.shishkin@linux.intel.com, alexandre.torgue@foss.st.com, ak@linux.intel.com, mingo@redhat.com, james.clark@arm.com, jolsa@kernel.org, john.garry@huawei.com, mark.rutland@arm.com, mcoquelin.stm32@gmail.com, namhyung@kernel.org, peterz@infradead.org, eranian@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lkp@lists.01.org, lkp@intel.com Subject: Re: [LKP] Re: [perf vendor events] 3f5f0df7bf: perf-sanity-tests.perf_all_metrics_test.fail Date: Wed, 13 Apr 2022 10:09:15 -0700 [thread overview] Message-ID: <CAP-5=fXj+WT3ExNo-fL4d9b_Wm5swnKaCWd67rU85Q=QFg5KUw@mail.gmail.com> (raw) In-Reply-To: <85eed89f-e4a8-2887-a0b3-579704304357@linux.intel.com> On Wed, Apr 13, 2022 at 9:37 AM Liang, Kan <kan.liang@linux.intel.com> wrote: > > > > On 4/13/2022 12:03 PM, Ian Rogers wrote: > > 3) Weak group doesn't fall back to no group: > > That's because the group validation code doesn't take pinned events, > such as the NMI watchdog, into account. > > I proposed a kernel patch to fix it, but it's rejected. It should be > hard to find a generic way to fix it from the kernel side. > https://lore.kernel.org/lkml/1565977750-76693-1-git-send-email-kan.liang@linux.intel.com/ > > Maybe we can workaround it from the perf tool side? > For example, for each weak group with cycles event and NMI watchdog is > enabled, add an extra cycles event when opening the group. If the open > fails with the extra cycles event, fall back to no group. After the > extra cycles event check, remove the extra cycles. > > What do you think? Thanks Kan, it is a shame the kernel support is lacking here. I'm not sure what you are proposing for the perf tool to do. So: > for each weak group with cycles event and NMI watchdog Okay, let's try Branching_Overhead as mentioned in this report - but the event is CPU_CLK_UNHALTED.THREAD here :-/ > add an extra cycles event when opening the group So the perf_event_open doesn't fail here for me: $ perf stat -e '{BR_INST_RETIRED.NEAR_CALL,BR_INST_RETIRED.NEAR_TAKEN,BR_INST_RETIRED.NOT_TAKEN,BR_INST_RETIRED.CONDITIONAL,CPU_CLK_UNHALTED.THREAD},cycles' -a sleep 1 Performance counter stats for 'system wide': <not counted> BR_INST_RETIRED.NEAR_CALL (0.00%) <not counted> BR_INST_RETIRED.NEAR_TAKEN (0.00%) <not counted> BR_INST_RETIRED.NOT_TAKEN (0.00%) <not counted> BR_INST_RETIRED.CONDITIONAL (0.00%) <not counted> CPU_CLK_UNHALTED.THREAD (0.00%) 4,071,908,022 cycles (49.97%) 0.998134717 seconds time elapsed Some events weren't counted. Try disabling the NMI watchdog: echo 0 > /proc/sys/kernel/nmi_watchdog perf stat ... echo 1 > /proc/sys/kernel/nmi_watchdog The events in group usually have to be from the same PMU. Try reorganizing the group. I'm not sure what the cycles event is achieving here, but it seems the behavior will need a kernel change. I think I'm misunderstanding your proposal :-) Thanks, Ian > Thanks, > Kan > > $ perf stat -e '{BR_INST_RETIRED.NEAR_CALL,BR_INST_RETIRED.NEAR_TAKEN,BR_INST_RETIRED.NOT_TAKEN,BR_INST_RETIRED.CONDITIONAL,CPU_CLK_UNHALTED.THREAD}:W' > > -a sleep 1 > > > > Performance counter stats for 'system wide': > > > > <not counted> BR_INST_RETIRED.NEAR_CALL > > (0.00%) > > <not counted> BR_INST_RETIRED.NEAR_TAKEN > > (0.00%) > > <not counted> BR_INST_RETIRED.NOT_TAKEN > > (0.00%) > > <not counted> BR_INST_RETIRED.CONDITIONAL > > (0.00%) > > <not counted> CPU_CLK_UNHALTED.THREAD > > (0.00%) > > > > 1.001690318 seconds time elapsed > > > > Some events weren't counted. Try disabling the NMI watchdog: > > echo 0 > /proc/sys/kernel/nmi_watchdog > > perf stat ... > > echo 1 > /proc/sys/kernel/nmi_watchdog
WARNING: multiple messages have this Message-ID (diff)
From: Ian Rogers <irogers@google.com> To: lkp@lists.01.org Subject: Re: [perf vendor events] 3f5f0df7bf: perf-sanity-tests.perf_all_metrics_test.fail Date: Wed, 13 Apr 2022 10:09:15 -0700 [thread overview] Message-ID: <CAP-5=fXj+WT3ExNo-fL4d9b_Wm5swnKaCWd67rU85Q=QFg5KUw@mail.gmail.com> (raw) In-Reply-To: <85eed89f-e4a8-2887-a0b3-579704304357@linux.intel.com> [-- Attachment #1: Type: text/plain, Size: 3337 bytes --] On Wed, Apr 13, 2022 at 9:37 AM Liang, Kan <kan.liang@linux.intel.com> wrote: > > > > On 4/13/2022 12:03 PM, Ian Rogers wrote: > > 3) Weak group doesn't fall back to no group: > > That's because the group validation code doesn't take pinned events, > such as the NMI watchdog, into account. > > I proposed a kernel patch to fix it, but it's rejected. It should be > hard to find a generic way to fix it from the kernel side. > https://lore.kernel.org/lkml/1565977750-76693-1-git-send-email-kan.liang(a)linux.intel.com/ > > Maybe we can workaround it from the perf tool side? > For example, for each weak group with cycles event and NMI watchdog is > enabled, add an extra cycles event when opening the group. If the open > fails with the extra cycles event, fall back to no group. After the > extra cycles event check, remove the extra cycles. > > What do you think? Thanks Kan, it is a shame the kernel support is lacking here. I'm not sure what you are proposing for the perf tool to do. So: > for each weak group with cycles event and NMI watchdog Okay, let's try Branching_Overhead as mentioned in this report - but the event is CPU_CLK_UNHALTED.THREAD here :-/ > add an extra cycles event when opening the group So the perf_event_open doesn't fail here for me: $ perf stat -e '{BR_INST_RETIRED.NEAR_CALL,BR_INST_RETIRED.NEAR_TAKEN,BR_INST_RETIRED.NOT_TAKEN,BR_INST_RETIRED.CONDITIONAL,CPU_CLK_UNHALTED.THREAD},cycles' -a sleep 1 Performance counter stats for 'system wide': <not counted> BR_INST_RETIRED.NEAR_CALL (0.00%) <not counted> BR_INST_RETIRED.NEAR_TAKEN (0.00%) <not counted> BR_INST_RETIRED.NOT_TAKEN (0.00%) <not counted> BR_INST_RETIRED.CONDITIONAL (0.00%) <not counted> CPU_CLK_UNHALTED.THREAD (0.00%) 4,071,908,022 cycles (49.97%) 0.998134717 seconds time elapsed Some events weren't counted. Try disabling the NMI watchdog: echo 0 > /proc/sys/kernel/nmi_watchdog perf stat ... echo 1 > /proc/sys/kernel/nmi_watchdog The events in group usually have to be from the same PMU. Try reorganizing the group. I'm not sure what the cycles event is achieving here, but it seems the behavior will need a kernel change. I think I'm misunderstanding your proposal :-) Thanks, Ian > Thanks, > Kan > > $ perf stat -e '{BR_INST_RETIRED.NEAR_CALL,BR_INST_RETIRED.NEAR_TAKEN,BR_INST_RETIRED.NOT_TAKEN,BR_INST_RETIRED.CONDITIONAL,CPU_CLK_UNHALTED.THREAD}:W' > > -a sleep 1 > > > > Performance counter stats for 'system wide': > > > > <not counted> BR_INST_RETIRED.NEAR_CALL > > (0.00%) > > <not counted> BR_INST_RETIRED.NEAR_TAKEN > > (0.00%) > > <not counted> BR_INST_RETIRED.NOT_TAKEN > > (0.00%) > > <not counted> BR_INST_RETIRED.CONDITIONAL > > (0.00%) > > <not counted> CPU_CLK_UNHALTED.THREAD > > (0.00%) > > > > 1.001690318 seconds time elapsed > > > > Some events weren't counted. Try disabling the NMI watchdog: > > echo 0 > /proc/sys/kernel/nmi_watchdog > > perf stat ... > > echo 1 > /proc/sys/kernel/nmi_watchdog
next prev parent reply other threads:[~2022-04-13 17:09 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-03-04 8:33 [perf vendor events] 3f5f0df7bf: perf-sanity-tests.perf_all_metrics_test.fail kernel test robot 2022-03-04 8:33 ` kernel test robot 2022-03-04 18:10 ` Ian Rogers 2022-03-04 18:10 ` Ian Rogers 2022-04-13 7:05 ` [LKP] " Carel Si 2022-04-13 7:05 ` Carel Si 2022-04-13 16:03 ` [LKP] " Ian Rogers 2022-04-13 16:03 ` Ian Rogers 2022-04-13 16:37 ` [LKP] " Liang, Kan 2022-04-13 16:37 ` Liang, Kan 2022-04-13 17:09 ` Ian Rogers [this message] 2022-04-13 17:09 ` Ian Rogers 2022-04-13 18:17 ` [LKP] " Liang, Kan 2022-04-13 18:17 ` Liang, Kan 2022-04-14 16:09 ` [LKP] " Ian Rogers 2022-04-14 16:09 ` Ian Rogers 2022-04-14 19:06 ` [LKP] " Liang, Kan 2022-04-14 19:06 ` Liang, Kan 2022-04-14 22:58 ` [LKP] " Namhyung Kim 2022-04-14 22:58 ` Namhyung Kim 2022-04-18 12:42 ` [LKP] " Liang, Kan 2022-04-18 12:42 ` Liang, Kan
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