From: Linus Torvalds <torvalds@linux-foundation.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
"the arch/x86 maintainers" <x86@kernel.org>,
Christoph Hellwig <hch@lst.de>,
Matthew Wilcox <willy@infradead.org>,
Daniel Vetter <daniel@ffwll.ch>,
Andrew Morton <akpm@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>, Ingo Molnar <mingo@kernel.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>,
Daniel Bristot de Oliveira <bristot@redhat.com>
Subject: Re: [patch V4 4/8] sched: Make migrate_disable/enable() independent of RT
Date: Thu, 19 Nov 2020 09:23:47 -0800 [thread overview]
Message-ID: <CAHk-=wire3dzhHx=KiL_f5Rj0=1u9ustsa33QoR-F9-v-NU9Ng@mail.gmail.com> (raw)
In-Reply-To: <20201119111411.GL3121378@hirez.programming.kicks-ass.net>
On Thu, Nov 19, 2020 at 3:14 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> I still hate all of this, and I really fear that with migrate_disable()
> available, people will be lazy and usage will increase :/
>
> Case at hand is this series, the only reason we need it here is because
> per-cpu page-tables are expensive...
No, I think you as a scheduler person just need to accept it.
Because this is certainly not the only time migration limiting has
come up, and no, it has absolutely nothing to do with per-cpu page
tables being completely unacceptable.
The scheduler people need to get used to this. Really. Because ASMP is
just going to be a fact.
There are few things more futile than railing against reality, Peter.
Honestly, the only argument I've ever heard against limiting migration
is the whole "our scheduling theory doesn't cover it".
So either throw the broken theory away, or live with it. Theory that
doesn't match reality isn't theory, it's religion.
Linus
next prev parent reply other threads:[~2020-11-19 17:24 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-18 19:48 [patch V4 0/8] mm/highmem: Preemptible variant of kmap_atomic & friends Thomas Gleixner
2020-11-18 19:48 ` [patch V4 1/8] mm/highmem: Provide and use CONFIG_DEBUG_KMAP_LOCAL Thomas Gleixner
2020-11-24 14:20 ` [tip: core/mm] " tip-bot2 for Thomas Gleixner
2020-11-18 19:48 ` [patch V4 2/8] mm/highmem: Provide CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP Thomas Gleixner
2020-11-18 21:13 ` Linus Torvalds
2020-11-19 8:46 ` Mel Gorman
2020-11-19 17:19 ` Linus Torvalds
2020-11-24 14:20 ` [tip: core/mm] " tip-bot2 for Thomas Gleixner
2020-11-18 19:48 ` [patch V4 3/8] x86: Support kmap_local() forced debugging Thomas Gleixner
2020-11-24 14:20 ` [tip: core/mm] " tip-bot2 for Thomas Gleixner
2021-01-06 23:01 ` [BUG] from " Steven Rostedt
2021-01-07 1:03 ` Linus Torvalds
2021-01-07 1:16 ` Steven Rostedt
2021-01-07 1:49 ` Steven Rostedt
2021-01-07 1:49 ` Jakub Kicinski
2021-01-07 2:11 ` Willem de Bruijn
2021-01-07 4:44 ` Willem de Bruijn
2021-01-07 19:47 ` Linus Torvalds
2021-01-07 20:52 ` Steven Rostedt
2021-01-07 21:07 ` Willem de Bruijn
2020-11-18 19:48 ` [patch V4 4/8] sched: Make migrate_disable/enable() independent of RT Thomas Gleixner
2020-11-19 9:38 ` Mel Gorman
2020-11-19 11:14 ` Peter Zijlstra
2020-11-19 12:14 ` Mel Gorman
2020-11-19 14:17 ` Steven Rostedt
2020-11-19 17:23 ` Linus Torvalds [this message]
2020-11-19 18:28 ` Peter Zijlstra
2020-11-20 1:33 ` Thomas Gleixner
2020-11-20 9:29 ` Peter Zijlstra
2020-11-22 23:16 ` Andy Lutomirski
2020-11-23 21:15 ` Thomas Gleixner
2020-11-23 21:25 ` Thomas Gleixner
2020-11-23 22:07 ` Andy Lutomirski
2020-11-23 23:10 ` Thomas Gleixner
2020-11-24 10:29 ` [tip: sched/core] " tip-bot2 for Thomas Gleixner
2020-11-18 19:48 ` [patch V4 5/8] sched: highmem: Store local kmaps in task struct Thomas Gleixner
2020-11-19 11:33 ` Peter Zijlstra
2020-11-19 11:51 ` Peter Zijlstra
2020-11-19 12:12 ` Peter Zijlstra
2020-11-19 14:11 ` Thomas Gleixner
2020-11-24 14:20 ` [tip: core/mm] " tip-bot2 for Thomas Gleixner
2020-11-18 19:48 ` [patch V4 6/8] mm/highmem: Provide kmap_local* Thomas Gleixner
2020-11-24 14:20 ` [tip: core/mm] " tip-bot2 for Thomas Gleixner
2020-11-18 19:48 ` [patch V4 7/8] io-mapping: Provide iomap_local variant Thomas Gleixner
2020-11-24 14:20 ` [tip: core/mm] " tip-bot2 for Thomas Gleixner
2020-11-18 19:48 ` [patch V4 8/8] x86/crashdump/32: Simplify copy_oldmem_page() Thomas Gleixner
2020-11-24 14:20 ` [tip: core/mm] " tip-bot2 for Thomas Gleixner
2020-11-24 8:03 ` [patch V4 0/8] mm/highmem: Preemptible variant of kmap_atomic & friends Peter Zijlstra
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