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From: Peter Zijlstra <peterz@infradead.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
	mingo@redhat.com, aarcange@redhat.com,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	rcu@vger.kernel.org, dm-devel@redhat.com, axboe@kernel.dk
Subject: Re: [dm-devel] [PATCH] sched: make struct task_struct::state 32-bit
Date: Tue, 3 Sep 2019 09:13:26 +0200	[thread overview]
Message-ID: <20190903071326.GV2369@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190903065155.GA28322@infradead.org>

On Mon, Sep 02, 2019 at 11:51:55PM -0700, Christoph Hellwig wrote:
> On Tue, Sep 03, 2019 at 12:05:58AM +0300, Alexey Dobriyan wrote:
> > 32-bit accesses are shorter than 64-bit accesses on x86_64.
> > Nothing uses 64-bitness of ->state.
> > 
> > Space savings are ~2KB on F30 kernel config.
> 
> I guess we'd save even more when moving from a volatile to
> WRITE_ONCE/READ_ONCE..

I doubt it; pretty much all accesses really should be using that.

Not saying we shouldn't maybe do that; but that's going to be massive
churn.

  reply	other threads:[~2019-09-03  7:13 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-02 21:05 [PATCH] sched: make struct task_struct::state 32-bit Alexey Dobriyan
2019-09-02 23:02 ` Valentin Schneider
2019-09-03 16:23   ` Alexey Dobriyan
2019-09-03 16:31     ` Valentin Schneider
2019-09-03  6:51 ` [dm-devel] " Christoph Hellwig
2019-09-03  7:13   ` Peter Zijlstra [this message]
2019-09-03 17:29 ` Valentin Schneider
2019-09-03 18:19   ` Alexey Dobriyan
2019-09-03 21:51     ` Valentin Schneider
2019-09-04 12:07       ` Valentin Schneider
2019-09-04 17:48         ` Valentin Schneider
2019-09-05 15:51         ` Markus Elfring
2019-09-05 16:52           ` Valentin Schneider
2019-09-23 10:26             ` Valentin Schneider
2019-09-23 10:34               ` Julia Lawall
2019-09-23 11:26                 ` Valentin Schneider
2019-09-23 11:43                   ` Julia Lawall
2019-09-23 13:23                     ` Valentin Schneider
2019-09-24  8:28                   ` Markus Elfring
2019-09-24  8:07               ` Markus Elfring
2019-09-04  9:43     ` [PATCH] " David Laight
2019-09-04 10:25       ` Valentin Schneider

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