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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Kent Overstreet <kent.overstreet@linux.dev>
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.
Message-ID: <20240630211142.kZAs9f0p@linutronix.de>
References: <20240621102750.oH9p1FQq@linutronix.de>
 <20240628094944.QwcHkf8J@linutronix.de>
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 <20240628195553.G48MpeQ6@linutronix.de>
 <w2qopormdwuh54vropw6sgvadnivjnrgvmpurud2cu6nannfj3@xxrs2r6qt7zi>
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In-Reply-To: <w2qopormdwuh54vropw6sgvadnivjnrgvmpurud2cu6nannfj3@xxrs2r6qt7zi>

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".

Sebastian