From: Thomas Gleixner <tglx@linutronix.de>
To: Alexey Dobriyan <adobriyan@gmail.com>,
mingo@redhat.com, peterz@infradead.org
Cc: linux-kernel@vger.kernel.org,
Alexey Dobriyan <adobriyan@gmail.com>,
x86@kernel.org
Subject: Re: [PATCH 1/4] sched: make nr_running() return 32-bit
Date: Thu, 13 May 2021 01:58:16 +0200 [thread overview]
Message-ID: <87fsyr5wtj.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20210422200228.1423391-1-adobriyan@gmail.com>
Alexey,
On Thu, Apr 22 2021 at 23:02, Alexey Dobriyan wrote:
> Creating 2**32 tasks is impossible due to futex pid limits and wasteful
> anyway. Nobody has done it.
>
this whole pile lacks useful numbers. What's the actual benefit of that
churn?
Just with the default config for one of my reference machines:
text data bss dec hex filename
16679864 6627950 1671296 24979110 17d26a6 ../build/vmlinux-before
16679894 6627950 1671296 24979140 17d26c4 ../build/vmlinux-after
------------------------------------------------------------------------
+30
I'm truly impressed by the massive savings of this change and I'm even
more impressed by the justification:
> Bring nr_running() into 32-bit world to save on REX prefixes.
Aside of the obvious useless churn, REX prefixes are universaly true for
all architectures, right? There is a world outside x86 ...
Thanks,
tglx
next prev parent reply other threads:[~2021-05-13 0:23 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-22 20:02 [PATCH 1/4] sched: make nr_running() return 32-bit Alexey Dobriyan
2021-04-22 20:02 ` [PATCH 2/4] sched: make nr_iowait() return 32-bit value Alexey Dobriyan
2021-05-12 20:01 ` [tip: sched/core] sched: Make " tip-bot2 for Alexey Dobriyan
2021-04-22 20:02 ` [PATCH 3/4] sched: make nr_iowait_cpu() return 32-bit Alexey Dobriyan
2021-05-12 20:01 ` [tip: sched/core] sched: Make nr_iowait_cpu() return 32-bit value tip-bot2 for Alexey Dobriyan
2021-04-22 20:02 ` [PATCH 4/4] sched: make multiple runqueue task counters 32-bit Alexey Dobriyan
2021-05-12 19:36 ` Ingo Molnar
2021-05-12 20:01 ` [tip: sched/core] sched: Make " tip-bot2 for Alexey Dobriyan
2021-05-12 20:01 ` [tip: sched/core] sched: Make nr_running() return 32-bit value tip-bot2 for Alexey Dobriyan
2021-05-12 23:58 ` Thomas Gleixner [this message]
2021-05-13 7:23 ` [PATCH 1/4] sched: make nr_running() return 32-bit Alexey Dobriyan
2021-05-13 9:58 ` Ingo Molnar
2021-05-13 21:22 ` Alexey Dobriyan
2021-05-14 12:52 ` Thomas Gleixner
2021-05-14 18:18 ` Thomas Gleixner
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