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From: Matthew Wilcox <willy@infradead.org>
To: Barry Song <21cnbao@gmail.com>
Cc: gaoxu <gaoxu2@honor.com>, Mike Rapoport <rppt@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"surenb@google.com" <surenb@google.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	yipengxiang <yipengxiang@honor.com>
Subject: Re: [PATCH] mm: simplify zone_idx()
Date: Mon, 14 Apr 2025 00:20:44 +0100	[thread overview]
Message-ID: <Z_xGzAx13diuCdvv@casper.infradead.org> (raw)
In-Reply-To: <CAGsJ_4x+5Pm6r655k+H9A67-d9AchD9qgsEKgU5oY6N1=JbTRA@mail.gmail.com>

On Mon, Apr 14, 2025 at 09:57:26AM +1200, Barry Song wrote:
> On Sat, Apr 12, 2025 at 10:06 PM gaoxu <gaoxu2@honor.com> wrote:
> > The zone info obtained through T32 in the Android 15-6.6 system(arm64):
> > (struct zone) struct (1664 bytes,
>
> I don't have a strong opinion on whether we need `zone_idx`—I'm okay
> with having it or not. If you'd like to add it, feel free to send out
> a v2 noting that it doesn't increase the struct size. If no one
> objects, it might be a nice cleanup.

Plus it's already 1664 bytes!  And we have, what, 4 zones per NUMA node?
Growing it doesn't feel like a big deal.  Although "saves two assembly
instructions" is also not exactly a big win.  If it saved a cacheline
reference, that might be more interesting, but it seems like it's more
likely to introduce a cacheline reference than save one.  Maybe just
not worth doing?


  reply	other threads:[~2025-04-13 23:20 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-10 12:03 gaoxu
2025-04-10 14:41 ` Mike Rapoport
2025-04-10 21:59   ` Barry Song
2025-04-12  8:34     ` 回复: " gaoxu
2025-04-12  9:15       ` Barry Song
2025-04-12 10:06         ` 回复: " gaoxu
2025-04-13 21:57           ` Barry Song
2025-04-13 23:20             ` Matthew Wilcox [this message]
2025-04-15 12:34               ` gaoxu
2025-04-15 14:49                 ` Matthew Wilcox

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