linux-kernel - Re: [PATCH v2] Reorder some fields in struct rq.

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Message-ID: <CABk29Ns_YttEU29AhREcNv-vqxDC2jEvFL-5MyhZh1RReecYsg@mail.gmail.com>
Date: Wed, 20 Aug 2025 17:11:14 -0700
From: Josh Don <joshdon@...gle.com>
To: Blake Jones <blakejones@...gle.com>
Cc: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, 
	Juri Lelli <juri.lelli@...hat.com>, Vincent Guittot <vincent.guittot@...aro.org>, 
	Madadi Vineeth Reddy <vineethr@...ux.ibm.com>, Dietmar Eggemann <dietmar.eggemann@....com>, 
	Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>, 
	Valentin Schneider <vschneid@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] Reorder some fields in struct rq.

Hi Blake,

On Wed, Jul 30, 2025 at 1:56 PM Blake Jones <blakejones@...gle.com> wrote:
>
> This colocates some hot fields in "struct rq" to be on the same cache line
> as others that are often accessed at the same time or in similar ways.
>

Thanks for the analysis and this patch.

I was going to suggest ____cacheline_aligned_in_smp, but it'll behave
nearly identical in practice so it doesn't matter (would save 64 bytes
on a 128 byte cacheline UP system).

Peter, any thoughts on this patch?

Best,
Josh