From: Kent Overstreet <kent.overstreet@linux.dev>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Ben Segall <bsegall@google.com>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Klara Modin <klarasmodin@gmail.com>,
Mel Gorman <mgorman@suse.de>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Suren Baghdasaryan <surenb@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Valentin Schneider <vschneid@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>
Subject: Re: [PATCH] sched/task_struct: Move alloc_tag to the end of the struct.
Date: Sun, 30 Jun 2024 17:23:36 -0400 [thread overview]
Message-ID: <jvkmjjqfo6w4arluq3ggwilfwucvg5ra273ziq5ov2e2hnrtck@x64ksn72qi3u> (raw)
In-Reply-To: <20240630211142.kZAs9f0p@linutronix.de>
On Sun, Jun 30, 2024 at 11:11:42PM GMT, Sebastian Andrzej Siewior wrote:
> On 2024-06-28 16:20:27 [-0400], Kent Overstreet wrote:
> > > Kent, you said you didn't want it where it currently is. Fine. You said
> > > you want it at the front next to `flags'. This isn't going to work since
> > > there is no space left. You didn't make another suggestion or say how to
> > > make room.
> >
> > It doesn't need to be on the exact same cacheline, just as near as you
> > can get it.
>
> the first possible thing would be somewhere after the scheduler.
> However, what difference does it make if it s two cache lines later or
> more? I don't understand the requirement "closer".
take advantage of CPU prefetching; CPUs will bring in more than just the
cacheline you touched because 64 bytes is small and it's cheap to fetch
from the same DRAM bank while it's open.
next prev parent reply other threads:[~2024-06-30 21:23 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-21 10:27 Sebastian Andrzej Siewior
2024-06-21 14:20 ` Kent Overstreet
2024-06-21 18:29 ` Sebastian Andrzej Siewior
2024-06-21 18:49 ` Kent Overstreet
2024-06-21 19:07 ` Sebastian Andrzej Siewior
2024-06-21 19:13 ` Kent Overstreet
2024-06-21 19:22 ` Sebastian Andrzej Siewior
2024-06-28 9:49 ` Sebastian Andrzej Siewior
2024-06-28 19:20 ` Andrew Morton
2024-06-28 19:35 ` Kent Overstreet
2024-06-28 19:55 ` Sebastian Andrzej Siewior
2024-06-28 20:20 ` Kent Overstreet
2024-06-30 21:11 ` Sebastian Andrzej Siewior
2024-06-30 21:23 ` Kent Overstreet [this message]
2024-07-01 8:05 ` Sebastian Andrzej Siewior
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