linux-kernel - Re: [PATCH] mm: page_alloc: simpify page del and expand

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Message-Id: <20240827175959.8f0e9a228407a7be16b328c1@linux-foundation.org>
Date: Tue, 27 Aug 2024 17:59:59 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Huan Yang <link@...o.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 opensource.kernel@...o.com
Subject: Re: [PATCH] mm: page_alloc: simpify page del and expand

On Mon, 26 Aug 2024 14:40:48 +0800 Huan Yang <link@...o.com> wrote:

> When page del from buddy and need expand, it will account free_pages
> in zone's migratetype.
> 
> The current way is to subtract the page number of the current order
> when deleting, and then add it back when expanding.
> 
> This is unnecessary, as when migrating the same type, we can directly
> record the difference between the high-order pages and the expand
> added, and then subtract it directly.
> 
> This patch merge that, only when del and expand done, then account
> free_pages.

It isn't obvious to me that this is a significant improvement.  Am I
missing something?