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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Uladzislau Rezki , Nick Terrell , David Sterba , Vishal Moola , linux-mm@kvack.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Ryan.Roberts@arm.com, david.hildenbrand@arm.com Cc: Muhammad Usama Anjum Subject: [PATCH v4 3/3] mm/page_alloc: Optimize __free_contig_frozen_range() Date: Fri, 27 Mar 2026 12:57:15 +0000 Message-ID: <20260327125720.2270651-4-usama.anjum@arm.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260327125720.2270651-1-usama.anjum@arm.com> References: <20260327125720.2270651-1-usama.anjum@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: F19AC100005 X-Stat-Signature: ck4hjzre7rb4o1pf9is4jjrwxyqnuhod X-Rspamd-Server: rspam06 X-HE-Tag: 1774616265-814176 X-HE-Meta: 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 AbjizWqC O9ctemq0TrJTHkOYzmAnJy6wNVvZRtq0lNFyQtTqVsl8GZ4pb9v3BcwsIMIZJyVx3lnCc28NcRqYPP5aRdomVtDcp8WdE4vnaMtxiP4TXOIVhYV6GyvmtxpF2vd7jR9Xn2y1g8zJKExlXVw0taaZpXHVGw7+xXMu6sHsE8O4X1iinjBLMY68t9Vb+sPCDeL/95NEBlAUn/49aApmcYt1BXIyuLV5+iXv+zas6EtWxgFuW5o+1JFOEaY9W6kfVqbhCv7he2mr0CxflkGLAHiHG41zLhWrAf73kqZrkyK0/avkoQxu33kPoNtfyzjVFrmwWWRRtBt6tbgHiIXB7O/8JyiVGY9Z0He7UN+LeQyx7ffA1gl3gJUjJ4gf9s9L7yAv6ccst Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Apply the same batch-freeing optimization from free_contig_range() to the frozen page path. The previous __free_contig_frozen_range() freed each order-0 page individually via free_frozen_pages(), which is slow for the same reason the old free_contig_range() was: each page goes to the order-0 pcp list rather than being coalesced into higher-order blocks. Rewrite __free_contig_frozen_range() to call free_pages_prepare() for each order-0 page, then batch the prepared pages into the largest possible power-of-2 aligned chunks via free_prepared_contig_range(). If free_pages_prepare() fails (e.g. HWPoison, bad page) the page is deliberately not freed; it should not be returned to the allocator. I've tested CMA through debugfs. The test allocates 16384 pages per allocation for several iterations. There is 3.5x improvement. Before: 1406 usec per iteration After: 402 usec per iteration Before: 70.89% 0.69% cma [kernel.kallsyms] [.] free_contig_frozen_range | |--70.20%--free_contig_frozen_range | | | |--46.41%--__free_frozen_pages | | | | | --36.18%--free_frozen_page_commit | | | | | --29.63%--_raw_spin_unlock_irqrestore | | | |--8.76%--_raw_spin_trylock | | | |--7.03%--__preempt_count_dec_and_test | | | |--4.57%--_raw_spin_unlock | | | |--1.96%--__get_pfnblock_flags_mask.isra.0 | | | --1.15%--free_frozen_page_commit | --0.69%--el0t_64_sync After: 23.57% 0.00% cma [kernel.kallsyms] [.] free_contig_frozen_range | ---free_contig_frozen_range | |--20.45%--__free_contig_frozen_range | | | |--17.77%--free_pages_prepare | | | --0.72%--free_prepared_contig_range | | | --0.55%--__free_frozen_pages | --3.12%--free_pages_prepare Suggested-by: Zi Yan Signed-off-by: Muhammad Usama Anjum --- Changes since v3: - Use newly introduced __free_contig_range_common() as the pattern was very similar to __free_contig_range() Changes since v2: - Rework the loop to check for memory sections just like __free_contig_range() - Didn't add reviewed-by tags because of rework --- mm/page_alloc.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 64be8a9019dca..110e912fa785e 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7059,8 +7059,7 @@ static int __alloc_contig_verify_gfp_mask(gfp_t gfp_mask, gfp_t *gfp_cc_mask) static void __free_contig_frozen_range(unsigned long pfn, unsigned long nr_pages) { - for (; nr_pages--; pfn++) - free_frozen_pages(pfn_to_page(pfn), 0); + __free_contig_range_common(pfn, nr_pages, true); } /** -- 2.47.3