linux-kernel - Re: [PATCH] mm/hugetlb: remove unnecessary memory fetch in PageHeadHuge()

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Date:   Thu, 12 Mar 2020 03:41:19 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Mike Kravetz <mike.kravetz@...cle.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/hugetlb: remove unnecessary memory fetch in
 PageHeadHuge()

On Wed, Mar 11, 2020 at 06:24:40PM +0100, Vlastimil Babka wrote:
> Commit f1e61557f023 ("mm: pack compound_dtor and compound_order into one word
> in struct page") changed compound_dtor from a pointer to an array index in
> order to pack it. To check if page has the hugeltbfs compound_dtor, we can
> just compare the index directly without fetching the function pointer.
> Said commit did that with PageHuge() and we can do the same with PageHeadHuge()
> to make the code a bit smaller and faster.
> 
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> Cc: Mike Kravetz <mike.kravetz@...cle.com>
> Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

We use literaly the same check in the function next to this one --
PageHuge().


-- 
 Kirill A. Shutemov