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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 v6 3/3] mm/page_alloc: Optimize __free_contig_frozen_range() Date: Wed, 1 Apr 2026 11:16:21 +0100 Message-ID: <20260401101634.2868165-4-usama.anjum@arm.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260401101634.2868165-1-usama.anjum@arm.com> References: <20260401101634.2868165-1-usama.anjum@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 56A128000B X-Stat-Signature: ikhc5hoisempm7zrbdxudcsrru5mtsb3 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1775038613-788998 X-HE-Meta: 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 /DN5bBSe tvXT0me74lhNdMzB0fpvwjjAtly8mb3HZ6VdjXSwhYOWCor9dTsmlVz1e0J8jMj2HxmDpinSom93E2wRQKtj0Dt9emsVjj6PqB8+38enFF7opczPsKXLlLs1yY0JEkfMo9sIWUx5WYcs5U/ytSmjG3CJ3clSurbPaKHYA+zjKslNyAAEi2YRcMAMk2PKhex/e5oRwrt4eXJq6G9MLX5LOzTvV6UZzpVZW1wUetCg7HJ5ofEkFDzpPfThe13XhINeeV9doMglUdbcKmxZqKDqywA2UwCviRUbDQrinxzyzrB+6vCA3+wj10wcYhqy5b5mhSd4GAvFhGSGEULqm7GsSGXui7hyGE1kAjVa/9c3hyDHqvjleKJ2G5ul/hP1rfRwajAfNnwtIyWCMQJQQUISG2aOMRA== 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 Acked-by: David Hildenbrand (Arm) Acked-by: Vlastimil Babka (SUSE) Reviewed-by: Zi Yan Suggested-by: Zi Yan Signed-off-by: Muhammad Usama Anjum --- Changes since v4: - Use /* */ style comment with boolean variable 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 6568af69b5cdb..dec72cedcf674 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7054,8 +7054,7 @@ 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, /* is_frozen= */ true); } /** -- 2.47.3