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Wed, 2 Oct 2024 16:39:38 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A41822004B; Wed, 2 Oct 2024 16:39:38 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 823E320040; Wed, 2 Oct 2024 16:39:31 +0000 (GMT) Received: from li-fdfde5cc-27d0-11b2-a85c-e224154bf6d4.ibm.com.com (unknown [9.43.25.182]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 2 Oct 2024 16:39:31 +0000 (GMT) From: Madadi Vineeth Reddy To: Arnaldo Carvalho de Melo , Namhyung Kim , Ian Rogers , Athira Rajeev , Peter Zijlstra , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Adrian Hunter , Kan Liang , acme@redhat.com, linux-perf-users , LKML Cc: Madadi Vineeth Reddy Subject: [PATCH v3] perf sched timehist: Add pre-migration wait time option Date: Wed, 2 Oct 2024 22:09:17 +0530 Message-ID: <20241002163917.33781-1-vineethr@linux.ibm.com> X-Mailer: git-send-email 2.43.2 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 087ItxpsiURvQ_a5ftdYFbGVa7ZTKaii X-Proofpoint-GUID: l6293BzQ-nftqBDYQ-BrNg57rr89TLIj X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1051,Hydra:6.0.680,FMLib:17.12.62.30 definitions=2024-10-02_16,2024-09-30_01,2024-09-30_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 bulkscore=0 mlxscore=0 priorityscore=1501 suspectscore=0 phishscore=0 adultscore=0 lowpriorityscore=0 mlxlogscore=999 impostorscore=0 spamscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2408220000 definitions=main-2410020117 pre-migration wait time is the time that a task unnecessarily spends on the runqueue of a CPU but doesn't get switched-in there. In terms of tracepoints, it is the time between sched:sched_wakeup and sched:sched_migrate_task. Let's say a task woke up on CPU2, then it got migrated to CPU4 and then it's switched-in to CPU4. So, here pre-migration wait time is time that it was waiting on runqueue of CPU2 after it is woken up. The general pattern for pre-migration to occur is: sched:sched_wakeup sched:sched_migrate_task sched:sched_switch The sched:sched_waking event is used to capture the wakeup time, as it aligns with the existing code and only introduces a negligible time difference. pre-migrations are generally not useful and it increases migrations. This metric would be helpful in testing patches mainly related to wakeup and load-balancer code paths as better wakeup logic would choose an optimal CPU where task would be switched-in and thereby reducing pre- migrations. The sample output(s) when -P or --pre-migrations is used: ================= time cpu task name wait time sch delay run time pre-mig time [tid/pid] (msec) (msec) (msec) (msec) --------------- ------ ------------------------------ --------- --------- --------- --------- 38456.720806 [0001] schbench[28634/28574] 4.917 4.768 1.004 0.000 38456.720810 [0001] rcu_preempt[18] 3.919 0.003 0.004 0.000 38456.721800 [0006] schbench[28779/28574] 23.465 23.465 1.999 0.000 38456.722800 [0002] schbench[28773/28574] 60.371 60.237 3.955 60.197 38456.722806 [0001] schbench[28634/28574] 0.004 0.004 1.996 0.000 38456.722811 [0001] rcu_preempt[18] 1.996 0.005 0.005 0.000 38456.723800 [0000] schbench[28833/28574] 4.000 4.000 3.999 0.000 38456.723800 [0004] schbench[28762/28574] 42.951 42.839 3.999 39.867 38456.723802 [0007] schbench[28812/28574] 43.947 43.817 3.999 40.866 38456.723804 [0001] schbench[28587/28574] 7.935 7.822 0.993 0.000 Signed-off-by: Madadi Vineeth Reddy --- Changes in v3: - Use the sched:sched_waking event to calculate the wakeup time. (Namhyung Kim) - Rebase against perf-tools-next commit 80f192724e31 ("perf tests: Add more topdown events regroup tests") Changes in v2: - Use timehist_sched_wakeup_event() to get the sched_wakeup time. (Namhyung Kim) - Rebase against perf-tools-next commit b38c49d8296b ("perf/test: Speed up test case perf annotate basic tests") Signed-off-by: Madadi Vineeth Reddy --- tools/perf/Documentation/perf-sched.txt | 8 +++ tools/perf/builtin-sched.c | 83 ++++++++++++++++--------- 2 files changed, 60 insertions(+), 31 deletions(-) diff --git a/tools/perf/Documentation/perf-sched.txt b/tools/perf/Documentation/perf-sched.txt index 3db64954a267..6dbbddb6464d 100644 --- a/tools/perf/Documentation/perf-sched.txt +++ b/tools/perf/Documentation/perf-sched.txt @@ -221,6 +221,14 @@ OPTIONS for 'perf sched timehist' priorities are specified with -: 120-129. A combination of both can also be provided: 0,120-129. +-P:: +--pre-migrations:: + Show pre-migration wait time. pre-migration wait time is the time spent + by a task waiting on a runqueue but not getting the chance to run there + and is migrated to a different runqueue where it is finally run. This + time between sched_wakeup and migrate_task is the pre-migration wait + time. + OPTIONS for 'perf sched replay' ------------------------------ diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c index fdf979aaf275..e6540803ced6 100644 --- a/tools/perf/builtin-sched.c +++ b/tools/perf/builtin-sched.c @@ -225,6 +225,7 @@ struct perf_sched { bool show_wakeups; bool show_next; bool show_migrations; + bool pre_migrations; bool show_state; bool show_prio; u64 skipped_samples; @@ -244,7 +245,9 @@ struct thread_runtime { u64 dt_iowait; /* time between CPU access by iowait (off cpu) */ u64 dt_preempt; /* time between CPU access by preempt (off cpu) */ u64 dt_delay; /* time between wakeup and sched-in */ + u64 dt_pre_mig; /* time between migration and wakeup */ u64 ready_to_run; /* time of wakeup */ + u64 migrated; /* time when a thread is migrated */ struct stats run_stats; u64 total_run_time; @@ -252,6 +255,7 @@ struct thread_runtime { u64 total_iowait_time; u64 total_preempt_time; u64 total_delay_time; + u64 total_pre_mig_time; char last_state; @@ -2073,14 +2077,15 @@ static void timehist_header(struct perf_sched *sched) printf(" "); } - if (sched->show_prio) { - printf(" %-*s %-*s %9s %9s %9s", - comm_width, "task name", MAX_PRIO_STR_LEN, "prio", - "wait time", "sch delay", "run time"); - } else { - printf(" %-*s %9s %9s %9s", comm_width, - "task name", "wait time", "sch delay", "run time"); - } + printf(" %-*s", comm_width, "task name"); + + if (sched->show_prio) + printf(" %-*s", MAX_PRIO_STR_LEN, "prio"); + + printf(" %9s %9s %9s", "wait time", "sch delay", "run time"); + + if (sched->pre_migrations) + printf(" %9s", "pre-mig time"); if (sched->show_state) printf(" %s", "state"); @@ -2095,17 +2100,15 @@ static void timehist_header(struct perf_sched *sched) if (sched->show_cpu_visual) printf(" %*s ", ncpus, ""); - if (sched->show_prio) { - printf(" %-*s %-*s %9s %9s %9s", - comm_width, "[tid/pid]", MAX_PRIO_STR_LEN, "", - "(msec)", "(msec)", "(msec)"); - } else { - printf(" %-*s %9s %9s %9s", comm_width, - "[tid/pid]", "(msec)", "(msec)", "(msec)"); - } + printf(" %-*s", comm_width, "[tid/pid]"); - if (sched->show_state) - printf(" %5s", ""); + if (sched->show_prio) + printf(" %-*s", MAX_PRIO_STR_LEN, ""); + + printf(" %9s %9s %9s", "(msec)", "(msec)", "(msec)"); + + if (sched->pre_migrations) + printf(" %9s", "(msec)"); printf("\n"); @@ -2117,15 +2120,15 @@ static void timehist_header(struct perf_sched *sched) if (sched->show_cpu_visual) printf(" %.*s ", ncpus, graph_dotted_line); - if (sched->show_prio) { - printf(" %.*s %.*s %.9s %.9s %.9s", - comm_width, graph_dotted_line, MAX_PRIO_STR_LEN, graph_dotted_line, - graph_dotted_line, graph_dotted_line, graph_dotted_line); - } else { - printf(" %.*s %.9s %.9s %.9s", comm_width, - graph_dotted_line, graph_dotted_line, graph_dotted_line, - graph_dotted_line); - } + printf(" %.*s", comm_width, graph_dotted_line); + + if (sched->show_prio) + printf(" %.*s", MAX_PRIO_STR_LEN, graph_dotted_line); + + printf(" %.9s %.9s %.9s", graph_dotted_line, graph_dotted_line, graph_dotted_line); + + if (sched->pre_migrations) + printf(" %.9s", graph_dotted_line); if (sched->show_state) printf(" %.5s", graph_dotted_line); @@ -2180,6 +2183,8 @@ static void timehist_print_sample(struct perf_sched *sched, print_sched_time(tr->dt_delay, 6); print_sched_time(tr->dt_run, 6); + if (sched->pre_migrations) + print_sched_time(tr->dt_pre_mig, 6); if (sched->show_state) printf(" %5c ", thread__tid(thread) == 0 ? 'I' : state); @@ -2239,6 +2244,7 @@ static void timehist_update_runtime_stats(struct thread_runtime *r, r->dt_iowait = 0; r->dt_preempt = 0; r->dt_run = 0; + r->dt_pre_mig = 0; if (tprev) { r->dt_run = t - tprev; @@ -2247,6 +2253,11 @@ static void timehist_update_runtime_stats(struct thread_runtime *r, pr_debug("time travel: wakeup time for task > previous sched_switch event\n"); else r->dt_delay = tprev - r->ready_to_run; + + if (r->ready_to_run && r->migrated) { + if ((r->migrated > r->ready_to_run) && (r->migrated < tprev)) + r->dt_pre_mig = r->migrated - r->ready_to_run; + } } if (r->last_time > tprev) @@ -2270,6 +2281,7 @@ static void timehist_update_runtime_stats(struct thread_runtime *r, r->total_sleep_time += r->dt_sleep; r->total_iowait_time += r->dt_iowait; r->total_preempt_time += r->dt_preempt; + r->total_pre_mig_time += r->dt_pre_mig; } static bool is_idle_sample(struct perf_sample *sample, @@ -2684,8 +2696,14 @@ static int timehist_migrate_task_event(const struct perf_tool *tool, tr->migrations++; + if (tr->migrated == 0) + tr->migrated = sample->time; + /* show migrations if requested */ - timehist_print_migration_event(sched, evsel, sample, machine, thread); + if (sched->show_migrations) { + timehist_print_migration_event(sched, evsel, sample, + machine, thread); + } return 0; } @@ -2836,11 +2854,13 @@ static int timehist_sched_change_event(const struct perf_tool *tool, /* last state is used to determine where to account wait time */ tr->last_state = state; - /* sched out event for task so reset ready to run time */ + /* sched out event for task so reset ready to run time and migrated time */ if (state == 'R') tr->ready_to_run = t; else tr->ready_to_run = 0; + + tr->migrated = 0; } evsel__save_time(evsel, sample->time, sample->cpu); @@ -3280,8 +3300,8 @@ static int perf_sched__timehist(struct perf_sched *sched) goto out; } - if (sched->show_migrations && - perf_session__set_tracepoints_handlers(session, migrate_handlers)) + if ((sched->show_migrations || sched->pre_migrations) && + perf_session__set_tracepoints_handlers(session, migrate_handlers)) goto out; /* pre-allocate struct for per-CPU idle stats */ @@ -3823,6 +3843,7 @@ int cmd_sched(int argc, const char **argv) OPT_BOOLEAN(0, "show-prio", &sched.show_prio, "Show task priority"), OPT_STRING(0, "prio", &sched.prio_str, "prio", "analyze events only for given task priority(ies)"), + OPT_BOOLEAN('P', "pre-migrations", &sched.pre_migrations, "Show pre-migration wait time"), OPT_PARENT(sched_options) }; -- 2.43.2