From: Linus Torvalds <torvalds@linux-foundation.org>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Qais Yousef <qyousef@layalina.io>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Ingo Molnar <mingo@kernel.org>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Juri Lelli <juri.lelli@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Valentin Schneider <vschneid@redhat.com>
Subject: Re: [GIT PULL] Scheduler changes for v6.8
Date: Fri, 12 Jan 2024 12:30:18 -0800 [thread overview]
Message-ID: <CAHk-=wiwRb50-q6EFU9RgjxOXHC2=x_ddQ6yzWTs5ah0nVeXPw@mail.gmail.com> (raw)
In-Reply-To: <CAKfTPtBQZcDpiPMF2sjJopNueMe+Lv0cziPzAMAaxH1XbfHiUQ@mail.gmail.com>
Ok, so testing a bit more. On a working kernel, when I do an empty
"make" (which is the fast test I've used), it's all single-threaded
because it's just 'make' doing tons of stat calls and string
operations.
And "cat /proc/cpuinfo | grep MHz" shows a nice clear signal:
...
cpu MHz : 2200.000
cpu MHz : 2200.000
cpu MHz : 4425.339
cpu MHz : 2200.000
...
so it boosts up to the top boost frequency.
Without the revert, doing the same thing, what I see is very
different. It's all just
...
cpu MHz : 2200.000
cpu MHz : 2200.000
cpu MHz : 2200.000
cpu MHz : 2200.000
...
which certainly explains why it takes 45s rather than 22s to do a full
empty build.
Btw, the "full empty build" I do is literally just
timestamp sh -c "make -j128 > ../makes"
where 'timestamp' is my stupid little wrapper program that just shows
elapsed time as the command is progressing (as opposed to "time",
which just shows it at the end).
Side note: that 4425.339 is very much the boost frequency, 'cpupower' reports
$ cpupower frequency-info
analyzing CPU 0:
driver: acpi-cpufreq
CPUs which run at the same hardware frequency: 0
CPUs which need to have their frequency coordinated by software: 0
maximum transition latency: Cannot determine or is not supported.
hardware limits: 2.20 GHz - 3.70 GHz
available frequency steps: 3.70 GHz, 2.80 GHz, 2.20 GHz
available cpufreq governors: conservative ondemand userspace
powersave performance schedutil
current policy: frequency should be within 2.20 GHz and 3.70 GHz.
The governor "schedutil" may decide which speed to use
within this range.
current CPU frequency: Unable to call hardware
current CPU frequency: 2.20 GHz (asserted by call to kernel)
boost state support:
Supported: yes
Active: no
and for all I know the scheduler got confused by the fact that it
thinks the hardware limits are 2.2-3.7 GHz. But the 3970X has a boost
frequency of 4.5GHz, and yes, I very much want it.
I will test Vincent's test-patch next.
Linus
next prev parent reply other threads:[~2024-01-12 20:30 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-28 12:23 [GIT PULL] Scheduler changes for v6.7 Ingo Molnar
2023-10-30 23:50 ` pr-tracker-bot
2024-01-08 14:07 ` [GIT PULL] Scheduler changes for v6.8 Ingo Molnar
2024-01-09 4:04 ` pr-tracker-bot
2024-01-10 22:19 ` Linus Torvalds
2024-01-10 22:41 ` Linus Torvalds
2024-01-10 22:57 ` Linus Torvalds
2024-01-11 8:11 ` Vincent Guittot
2024-01-11 17:45 ` Linus Torvalds
2024-01-11 17:53 ` Linus Torvalds
2024-01-11 18:16 ` Vincent Guittot
2024-01-12 14:23 ` Dietmar Eggemann
2024-01-12 16:58 ` Vincent Guittot
2024-01-12 18:18 ` Qais Yousef
2024-01-12 19:03 ` Vincent Guittot
2024-01-12 20:30 ` Linus Torvalds [this message]
2024-01-12 20:49 ` Linus Torvalds
2024-01-12 21:04 ` Linus Torvalds
2024-01-13 1:04 ` Qais Yousef
2024-01-13 1:24 ` Linus Torvalds
2024-01-13 1:31 ` Linus Torvalds
2024-01-13 10:47 ` Vincent Guittot
2024-01-13 18:33 ` Qais Yousef
2024-01-13 18:37 ` Qais Yousef
2024-01-11 11:09 ` [GIT PULL] scheduler fixes Ingo Molnar
2024-01-11 13:04 ` Vincent Guittot
2024-01-11 20:48 ` [PATCH] Revert "sched/cpufreq: Rework schedutil governor performance estimation" and dependent commit Ingo Molnar
2024-01-11 22:22 ` Vincent Guittot
2024-01-12 18:24 ` Ingo Molnar
2024-01-12 18:26 ` [GIT PULL] Scheduler changes for v6.8 Ingo Molnar
2024-01-14 9:12 ` Wyes Karny
2024-01-14 11:18 ` Vincent Guittot
2024-01-14 12:37 ` Wyes Karny
2024-01-14 13:02 ` Dietmar Eggemann
2024-01-14 13:05 ` Vincent Guittot
2024-01-14 13:03 ` Vincent Guittot
2024-01-14 15:12 ` Qais Yousef
2024-01-14 15:20 ` Vincent Guittot
2024-01-14 19:58 ` Qais Yousef
2024-01-14 23:37 ` Qais Yousef
2024-01-15 6:25 ` Wyes Karny
2024-01-15 11:59 ` Qais Yousef
2024-01-15 8:21 ` Vincent Guittot
2024-01-15 12:09 ` Qais Yousef
2024-01-15 13:26 ` Vincent Guittot
2024-01-15 14:03 ` Dietmar Eggemann
2024-01-15 15:26 ` Vincent Guittot
2024-01-15 20:05 ` Dietmar Eggemann
2024-01-15 8:42 ` David Laight
2024-01-14 18:11 ` Wyes Karny
2024-01-14 18:18 ` Vincent Guittot
2024-01-11 9:33 ` Ingo Molnar
2024-01-11 11:14 ` [tip: sched/urgent] Revert "sched/cpufreq: Rework schedutil governor performance estimation" and dependent commits tip-bot2 for Ingo Molnar
2024-01-11 20:55 ` [tip: sched/urgent] Revert "sched/cpufreq: Rework schedutil governor performance estimation" and dependent commit tip-bot2 for Ingo Molnar
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