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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 v5 3/3] mm/page_alloc: Optimize __free_contig_frozen_range() Date: Tue, 31 Mar 2026 16:22:01 +0100 Message-ID: <20260331152208.975266-4-usama.anjum@arm.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260331152208.975266-1-usama.anjum@arm.com> References: <20260331152208.975266-1-usama.anjum@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 366D680016 X-Stat-Signature: jg84uoon5wgbcwzzs1gbodz9iogm8ic9 X-Rspam-User: X-HE-Tag: 1774970546-229569 X-HE-Meta: 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 LKIvok+N ZVfJA5s2Hah+TeiYIceLo8yuYBGUnveipQaY7PSUUJ6cTmW/rU3Pc0WNvCn7jukDgMe2ja8PVLJuWrlnVpGyysftJeYQ9GgBy1McnkfHYmciKiK7j1vpr+DwLXB0z3MEJ1YNQmG0US7T/HobTNQjMTwtod7pmZTYtvdfHn71dF1WwBAdwtmA3W3YKJv6ksugO8mlyoKcbpHxTa7QMAI7cYjx8h+PalMdrQVB31FsEzIJCGfghw9McdOaczmPcxk8Qz3h4e+nbKakvS9MdVcQn1twvF4Sg258E/M3fciB7GebdVjzSjLwJm8dBrG2LW1x7NQtHistlOX8SKQowoC2PXYhZdiccZbGYEJcn+YKIc2TIgorCaf7GwleBnrXj5Ji6r82u5A44OgzG2FxZpgFMEuuC0A== 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 9218fda8842a6..b043b56f65c57 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7052,8 +7052,7 @@ 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