From: Muchun Song <muchun.song@linux.dev>
To: Kiryl Shutsemau <kas@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Usama Arif <usamaarif642@gmail.com>,
Frank van der Linden <fvdl@google.com>,
Oscar Salvador <osalvador@suse.de>,
Mike Rapoport <rppt@kernel.org>, Vlastimil Babka <vbabka@suse.cz>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Zi Yan <ziy@nvidia.com>, Baoquan He <bhe@redhat.com>,
Michal Hocko <mhocko@suse.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Jonathan Corbet <corbet@lwn.net>,
kernel-team@meta.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org
Subject: Re: [PATCHv2 13/14] mm: Remove the branch from compound_head()
Date: Mon, 22 Dec 2025 14:30:56 +0800 [thread overview]
Message-ID: <324C52CD-0E8C-412F-BA33-0F605C1B7AC3@linux.dev> (raw)
In-Reply-To: <20251218150949.721480-14-kas@kernel.org>
> On Dec 18, 2025, at 23:09, Kiryl Shutsemau <kas@kernel.org> wrote:
>
> The compound_head() function is a hot path. For example, the zap path
> calls it for every leaf page table entry.
>
> Rewrite the helper function in a branchless manner to eliminate the risk
> of CPU branch misprediction.
>
> Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Thanks.
next prev parent reply other threads:[~2025-12-22 6:32 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-18 15:09 [PATCHv2 00/14] Kiryl Shutsemau
2025-12-18 15:09 ` [PATCHv2 01/14] mm: Move MAX_FOLIO_ORDER definition to mmzone.h Kiryl Shutsemau
2025-12-18 15:09 ` [PATCHv2 02/14] mm/sparse: Check memmap alignment Kiryl Shutsemau
2025-12-22 8:34 ` Muchun Song
2025-12-22 14:02 ` Kiryl Shutsemau
2025-12-22 14:18 ` David Hildenbrand (Red Hat)
2025-12-22 14:52 ` Kiryl Shutsemau
2025-12-22 14:59 ` Muchun Song
2025-12-22 14:55 ` Muchun Song
2025-12-23 9:38 ` David Hildenbrand (Red Hat)
2025-12-23 11:26 ` Muchun Song
2025-12-24 14:13 ` Kiryl Shutsemau
2025-12-22 14:49 ` Muchun Song
2025-12-18 15:09 ` [PATCHv2 03/14] mm: Change the interface of prep_compound_tail() Kiryl Shutsemau
2025-12-22 2:55 ` Muchun Song
2025-12-18 15:09 ` [PATCHv2 04/14] mm: Rename the 'compound_head' field in the 'struct page' to 'compound_info' Kiryl Shutsemau
2025-12-22 3:00 ` Muchun Song
2025-12-18 15:09 ` [PATCHv2 05/14] mm: Move set/clear_compound_head() next to compound_head() Kiryl Shutsemau
2025-12-22 3:06 ` Muchun Song
2025-12-18 15:09 ` [PATCHv2 06/14] mm: Rework compound_head() for power-of-2 sizeof(struct page) Kiryl Shutsemau
2025-12-22 3:20 ` Muchun Song
2025-12-22 14:03 ` Kiryl Shutsemau
2025-12-23 8:37 ` Muchun Song
2025-12-22 7:57 ` Muchun Song
2025-12-22 9:45 ` Muchun Song
2025-12-22 14:49 ` Kiryl Shutsemau
2025-12-18 15:09 ` [PATCHv2 07/14] mm: Make page_zonenum() use head page Kiryl Shutsemau
2025-12-18 15:09 ` [PATCHv2 08/14] mm/hugetlb: Refactor code around vmemmap_walk Kiryl Shutsemau
2025-12-22 5:54 ` Muchun Song
2025-12-22 15:00 ` Kiryl Shutsemau
2025-12-22 15:11 ` Muchun Song
2025-12-18 15:09 ` [PATCHv2 09/14] mm/hugetlb: Remove fake head pages Kiryl Shutsemau
2025-12-18 15:09 ` [PATCHv2 10/14] mm: Drop fake head checks Kiryl Shutsemau
2025-12-22 5:56 ` Muchun Song
2025-12-18 15:09 ` [PATCHv2 11/14] hugetlb: Remove VMEMMAP_SYNCHRONIZE_RCU Kiryl Shutsemau
2025-12-22 6:00 ` Muchun Song
2025-12-18 15:09 ` [PATCHv2 12/14] mm/hugetlb: Remove hugetlb_optimize_vmemmap_key static key Kiryl Shutsemau
2025-12-22 6:03 ` Muchun Song
2025-12-18 15:09 ` [PATCHv2 13/14] mm: Remove the branch from compound_head() Kiryl Shutsemau
2025-12-22 6:30 ` Muchun Song [this message]
2025-12-18 15:09 ` [PATCHv2 14/14] hugetlb: Update vmemmap_dedup.rst Kiryl Shutsemau
2025-12-22 6:20 ` Muchun Song
2025-12-18 22:18 ` [PATCHv2 00/14] Eliminate fake head pages from vmemmap optimization Kiryl Shutsemau
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