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Wed, 19 Feb 2025 11:04:38 -0800 (PST) Received: from smtpclient.apple ([103.152.220.38]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-add3958ee01sm8939188a12.43.2025.02.19.11.04.34 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 19 Feb 2025 11:04:38 -0800 (PST) Content-Type: text/plain; charset=utf-8 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3826.400.131.1.6\)) Subject: Re: [PATCH 1/2] sched: Refine scheduler naming for clarity and specificity From: Jemmy Wong In-Reply-To: <20250219134210.51bdf447@gandalf.local.home> Date: Thu, 20 Feb 2025 03:04:02 +0800 Cc: Masami Hiramatsu , Mathieu Desnoyers , Mark Rutland , Jonathan Corbet , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Ben Segall , Mel Gorman , Valentin Schneider , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: <0245BA04-B0CD-482E-820A-FF5D608FB57E@gmail.com> References: <20250219182020.393006-1-jemmywong512@gmail.com> <20250219182020.393006-2-jemmywong512@gmail.com> <20250219134210.51bdf447@gandalf.local.home> To: Steven Rostedt X-Mailer: Apple Mail (2.3826.400.131.1.6) Hi Steve, =20 I=E2=80=99ve identified the cause: these changes stem from trailing = whitespace,=20 which my IDE automatically trims by default.=20 I=E2=80=99ll disable this setting to avoid generating large diffs going = forward. =20 Do I need to revert these changes? I don=E2=80=99t think it matters,=20 but I=E2=80=99d appreciate your guidance. =20 BR, Jemmy > On Feb 20, 2025, at 2:42=E2=80=AFAM, Steven Rostedt = wrote: >=20 > On Thu, 20 Feb 2025 02:20:19 +0800 > Jemmy Wong wrote: >=20 >> +++ b/Documentation/trace/ftrace.rst >> @@ -986,14 +986,14 @@ why a latency happened. Here is a typical = trace:: >> # =3D> ended at: _raw_spin_unlock_irqrestore >> # >> # >> - # _------=3D> CPU# >> - # / _-----=3D> irqs-off >> - # | / _----=3D> need-resched >> - # || / _---=3D> hardirq/softirq >> - # ||| / _--=3D> preempt-depth >> - # |||| / delay >> - # cmd pid ||||| time | caller >> - # \ / ||||| \ | / >> + # _------=3D> CPU# >> + # / _-----=3D> irqs-off >> + # | / _----=3D> need-resched >> + # || / _---=3D> hardirq/softirq >> + # ||| / _--=3D> preempt-depth >> + # |||| / delay >> + # cmd pid ||||| time | caller >> + # \ / ||||| \ | / >=20 > What exactly did you change for all these header updates? >=20 > -- Steve >=20 >> ps-6143 2d... 0us!: trace_hardirqs_off = <-__lock_task_sighand >> ps-6143 2d..1 259us+: trace_hardirqs_on = <-_raw_spin_unlock_irqrestore >> ps-6143 2d..1 263us+: time_hardirqs_on = <-_raw_spin_unlock_irqrestore >> @@ -1490,14 +1490,14 @@ an example:: >> # =3D> ended at: run_timer_softirq >> # >> # >> - # _------=3D> CPU# >> - # / _-----=3D> irqs-off >> - # | / _----=3D> need-resched >> - # || / _---=3D> hardirq/softirq >> - # ||| / _--=3D> preempt-depth >> - # |||| / delay >> - # cmd pid ||||| time | caller >> - # \ / ||||| \ | / >> + # _------=3D> CPU# >> + # / _-----=3D> irqs-off >> + # | / _----=3D> need-resched >> + # || / _---=3D> hardirq/softirq >> + # ||| / _--=3D> preempt-depth >> + # |||| / delay >> + # cmd pid ||||| time | caller >> + # \ / ||||| \ | / >> -0 0d.s2 0us+: _raw_spin_lock_irq = <-run_timer_softirq >> -0 0dNs3 17us : _raw_spin_unlock_irq = <-run_timer_softirq >> -0 0dNs3 17us+: trace_hardirqs_on = <-run_timer_softirq >> @@ -1541,14 +1541,14 @@ function-trace, we get a much larger output:: >> # =3D> ended at: ata_scsi_queuecmd >> # >> # >> - # _------=3D> CPU# >> - # / _-----=3D> irqs-off >> - # | / _----=3D> need-resched >> - # || / _---=3D> hardirq/softirq >> - # ||| / _--=3D> preempt-depth >> - # |||| / delay >> - # cmd pid ||||| time | caller >> - # \ / ||||| \ | / >> + # _------=3D> CPU# >> + # / _-----=3D> irqs-off >> + # | / _----=3D> need-resched >> + # || / _---=3D> hardirq/softirq >> + # ||| / _--=3D> preempt-depth >> + # |||| / delay >> + # cmd pid ||||| time | caller >> + # \ / ||||| \ | / >> bash-2042 3d... 0us : _raw_spin_lock_irqsave = <-ata_scsi_queuecmd >> bash-2042 3d... 0us : add_preempt_count = <-_raw_spin_lock_irqsave >> bash-2042 3d..1 1us : ata_scsi_find_dev = <-ata_scsi_queuecmd >> @@ -1689,14 +1689,14 @@ is much like the irqsoff tracer. >> # =3D> ended at: do_IRQ >> # >> # >> - # _------=3D> CPU# >> - # / _-----=3D> irqs-off >> - # | / _----=3D> need-resched >> - # || / _---=3D> hardirq/softirq >> - # ||| / _--=3D> preempt-depth >> - # |||| / delay >> - # cmd pid ||||| time | caller >> - # \ / ||||| \ | / >> + # _------=3D> CPU# >> + # / _-----=3D> irqs-off >> + # | / _----=3D> need-resched >> + # || / _---=3D> hardirq/softirq >> + # ||| / _--=3D> preempt-depth >> + # |||| / delay >> + # cmd pid ||||| time | caller >> + # \ / ||||| \ | / >> sshd-1991 1d.h. 0us+: irq_enter <-do_IRQ >> sshd-1991 1d..1 46us : irq_exit <-do_IRQ >> sshd-1991 1d..1 47us+: trace_preempt_on <-do_IRQ >> @@ -1727,14 +1727,14 @@ was over. >> # =3D> ended at: task_rq_unlock >> # >> # >> - # _------=3D> CPU# >> - # / _-----=3D> irqs-off >> - # | / _----=3D> need-resched >> - # || / _---=3D> hardirq/softirq >> - # ||| / _--=3D> preempt-depth >> - # |||| / delay >> - # cmd pid ||||| time | caller >> - # \ / ||||| \ | / >> + # _------=3D> CPU# >> + # / _-----=3D> irqs-off >> + # | / _----=3D> need-resched >> + # || / _---=3D> hardirq/softirq >> + # ||| / _--=3D> preempt-depth >> + # |||| / delay >> + # cmd pid ||||| time | caller >> + # \ / ||||| \ | / >> bash-1994 1d..1 0us : _raw_spin_lock_irqsave = <-wake_up_new_task >> bash-1994 1d..1 0us : select_task_rq_fair = <-select_task_rq >> bash-1994 1d..1 1us : __rcu_read_lock = <-select_task_rq_fair >> @@ -1841,14 +1841,14 @@ tracers. >> # =3D> ended at: ata_scsi_queuecmd >> # >> # >> - # _------=3D> CPU# >> - # / _-----=3D> irqs-off >> - # | / _----=3D> need-resched >> - # || / _---=3D> hardirq/softirq >> - # ||| / _--=3D> preempt-depth >> - # |||| / delay >> - # cmd pid ||||| time | caller >> - # \ / ||||| \ | / >> + # _------=3D> CPU# >> + # / _-----=3D> irqs-off >> + # | / _----=3D> need-resched >> + # || / _---=3D> hardirq/softirq >> + # ||| / _--=3D> preempt-depth >> + # |||| / delay >> + # cmd pid ||||| time | caller >> + # \ / ||||| \ | / >> ls-2230 3d... 0us+: _raw_spin_lock_irqsave = <-ata_scsi_queuecmd >> ls-2230 3...1 100us : _raw_spin_unlock_irqrestore = <-ata_scsi_queuecmd >> ls-2230 3...1 101us+: trace_preempt_on = <-ata_scsi_queuecmd >> @@ -1894,14 +1894,14 @@ Here is a trace with function-trace set:: >> # =3D> ended at: mutex_unlock >> # >> # >> - # _------=3D> CPU# >> - # / _-----=3D> irqs-off >> - # | / _----=3D> need-resched >> - # || / _---=3D> hardirq/softirq >> - # ||| / _--=3D> preempt-depth >> - # |||| / delay >> - # cmd pid ||||| time | caller >> - # \ / ||||| \ | / >> + # _------=3D> CPU# >> + # / _-----=3D> irqs-off >> + # | / _----=3D> need-resched >> + # || / _---=3D> hardirq/softirq >> + # ||| / _--=3D> preempt-depth >> + # |||| / delay >> + # cmd pid ||||| time | caller >> + # \ / ||||| \ | / >> kworker/-59 3...1 0us : __schedule <-schedule >> kworker/-59 3d..1 0us : rcu_preempt_qs = <-rcu_note_context_switch >> kworker/-59 3d..1 1us : add_preempt_count = <-_raw_spin_lock_irq >> @@ -1987,7 +1987,7 @@ wakeup >> One common case that people are interested in tracing is the >> time it takes for a task that is woken to actually wake up. >> Now for non Real-Time tasks, this can be arbitrary. But tracing >> -it nonetheless can be interesting. >> +it nonetheless can be interesting. >>=20 >> Without function tracing:: >>=20 >> @@ -2007,14 +2007,14 @@ Without function tracing:: >> # | task: kworker/3:1H-312 (uid:0 nice:-20 policy:0 rt_prio:0) >> # ----------------- >> # >> - # _------=3D> CPU# >> - # / _-----=3D> irqs-off >> - # | / _----=3D> need-resched >> - # || / _---=3D> hardirq/softirq >> - # ||| / _--=3D> preempt-depth >> - # |||| / delay >> - # cmd pid ||||| time | caller >> - # \ / ||||| \ | / >> + # _------=3D> CPU# >> + # / _-----=3D> irqs-off >> + # | / _----=3D> need-resched >> + # || / _---=3D> hardirq/softirq >> + # ||| / _--=3D> preempt-depth >> + # |||| / delay >> + # cmd pid ||||| time | caller >> + # \ / ||||| \ | / >> -0 3dNs7 0us : 0:120:R + [003] 312:100:R = kworker/3:1H >> -0 3dNs7 1us+: ttwu_do_activate.constprop.87 = <-try_to_wake_up >> -0 3d..3 15us : __schedule <-schedule >> @@ -2076,14 +2076,14 @@ Instead of performing an 'ls', we will run = 'sleep 1' under >> # | task: sleep-2389 (uid:0 nice:0 policy:1 rt_prio:5) >> # ----------------- >> # >> - # _------=3D> CPU# >> - # / _-----=3D> irqs-off >> - # | / _----=3D> need-resched >> - # || / _---=3D> hardirq/softirq >> - # ||| / _--=3D> preempt-depth >> - # |||| / delay >> - # cmd pid ||||| time | caller >> - # \ / ||||| \ | / >> + # _------=3D> CPU# >> + # / _-----=3D> irqs-off >> + # | / _----=3D> need-resched >> + # || / _---=3D> hardirq/softirq >> + # ||| / _--=3D> preempt-depth >> + # |||| / delay >> + # cmd pid ||||| time | caller >> + # \ / ||||| \ | / >> -0 3d.h4 0us : 0:120:R + [003] 2389: 94:R = sleep >> -0 3d.h4 1us+: ttwu_do_activate.constprop.87 = <-try_to_wake_up >> -0 3d..3 5us : __schedule <-schedule >> @@ -2125,19 +2125,19 @@ Doing the same with chrt -r 5 and = function-trace set. >> # | task: sleep-2448 (uid:0 nice:0 policy:1 rt_prio:5) >> # ----------------- >> # >> - # _------=3D> CPU# >> - # / _-----=3D> irqs-off >> - # | / _----=3D> need-resched >> - # || / _---=3D> hardirq/softirq >> - # ||| / _--=3D> preempt-depth >> - # |||| / delay >> - # cmd pid ||||| time | caller >> - # \ / ||||| \ | / >> + # _------=3D> CPU# >> + # / _-----=3D> irqs-off >> + # | / _----=3D> need-resched >> + # || / _---=3D> hardirq/softirq >> + # ||| / _--=3D> preempt-depth >> + # |||| / delay >> + # cmd pid ||||| time | caller >> + # \ / ||||| \ | /