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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 0/3] mm: Free contiguous order-0 pages efficiently Date: Tue, 31 Mar 2026 16:21:58 +0100 Message-ID: <20260331152208.975266-1-usama.anjum@arm.com> X-Mailer: git-send-email 2.47.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: E4D3814000D X-Stat-Signature: c8g7x93ngkfrh9zrtwrud4zc9tx683hf X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1774970537-822902 X-HE-Meta: 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 uUPqDl2f AXocmC2fxDIm7Fyt+d92TlAX+Z5FbJd4/8x8ex9ketVnNWaRTZLBtsu40I7EDTcRf5j+UOghCKhm8O0TW8rv2uMYuHq4euGTUbQFE40to+CHOHVk8nrYqfYSvMn4yU0XqEg+aZivxZup7n++9ObZlGsEwGtx301CgKpFhIP9d36QPiHgeFMKQX43ki+JXjS9czhLUtiR9sg7irzTVfVEphJVY5H5W4+ul1H53YkFL1nNGyWUveMDyjEJC0NAU/vFnbWGKWiJfyguZBFf1M0SNh+M+jXIblFxbak/qnXNk9B0iCto= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi All, A recent change to vmalloc caused some performance benchmark regressions (see [1]). I'm attempting to fix that (and at the same time significantly improve beyond the baseline) by freeing a contiguous set of order-0 pages as a batch. At the same time I observed that free_contig_range() was essentially doing the same thing as vfree() so I've fixed it there too. While at it, optimize the __free_contig_frozen_range() as well. Check that the contiguous range falls in the same section. If they aren't enabled, the if conditions get optimized out by the compiler as memdesc_section() returns 0. See num_pages_contiguous() for more details about it. [1] https://lore.kernel.org/all/66919a28-bc81-49c9-b68f-dd7c73395a0d@arm.com v6.18 - Before the patch causing regression was added mm-new - current latest code this series - v2 series of these patches (>0 is faster, <0 is slower, (R)/(I) = statistically significant Regression/Improvement) v6.18 vs mm-new +-----------------+----------------------------------------------------------+-------------------+-------------+ | Benchmark | Result Class | v6.18 (base) | mm-new | +=================+==========================================================+===================+=============+ | micromm/vmalloc | fix_align_alloc_test: p:1, h:0, l:500000 (usec) | 653643.33 | (R) -50.92% | | | fix_size_alloc_test: p:1, h:0, l:500000 (usec) | 366167.33 | (R) -11.96% | | | fix_size_alloc_test: p:4, h:0, l:500000 (usec) | 489484.00 | (R) -35.21% | | | fix_size_alloc_test: p:16, h:0, l:500000 (usec) | 1011250.33 | (R) -36.45% | | | fix_size_alloc_test: p:16, h:1, l:500000 (usec) | 1086812.33 | (R) -31.83% | | | fix_size_alloc_test: p:64, h:0, l:100000 (usec) | 657940.00 | (R) -38.62% | | | fix_size_alloc_test: p:64, h:1, l:100000 (usec) | 765422.00 | (R) -24.84% | | | fix_size_alloc_test: p:256, h:0, l:100000 (usec) | 2468585.00 | (R) -37.83% | | | fix_size_alloc_test: p:256, h:1, l:100000 (usec) | 2815758.33 | (R) -26.32% | | | fix_size_alloc_test: p:512, h:0, l:100000 (usec) | 4851969.00 | (R) -37.76% | | | fix_size_alloc_test: p:512, h:1, l:100000 (usec) | 4496257.33 | (R) -31.15% | | | full_fit_alloc_test: p:1, h:0, l:500000 (usec) | 570605.00 | -8.97% | | | kvfree_rcu_1_arg_vmalloc_test: p:1, h:0, l:500000 (usec) | 500866.00 | -5.88% | | | kvfree_rcu_2_arg_vmalloc_test: p:1, h:0, l:500000 (usec) | 499733.00 | -6.95% | | | long_busy_list_alloc_test: p:1, h:0, l:500000 (usec) | 5266237.67 | (R) -40.19% | | | pcpu_alloc_test: p:1, h:0, l:500000 (usec) | 490284.00 | -2.10% | | | random_size_align_alloc_test: p:1, h:0, l:500000 (usec) | 850986.33 | (R) -48.03% | | | random_size_alloc_test: p:1, h:0, l:500000 (usec) | 2712106.00 | (R) -40.48% | | | vm_map_ram_test: p:1, h:0, l:500000 (usec) | 111151.33 | 3.52% | +-----------------+----------------------------------------------------------+-------------------+-------------+ v6.18 vs mm-new with patches +-----------------+----------------------------------------------------------+-------------------+--------------+ | Benchmark | Result Class | v6.18 (base) | this series | +=================+==========================================================+===================+==============+ | micromm/vmalloc | fix_align_alloc_test: p:1, h:0, l:500000 (usec) | 653643.33 | -14.02% | | | fix_size_alloc_test: p:1, h:0, l:500000 (usec) | 366167.33 | -7.23% | | | fix_size_alloc_test: p:4, h:0, l:500000 (usec) | 489484.00 | -1.57% | | | fix_size_alloc_test: p:16, h:0, l:500000 (usec) | 1011250.33 | 1.57% | | | fix_size_alloc_test: p:16, h:1, l:500000 (usec) | 1086812.33 | (I) 15.75% | | | fix_size_alloc_test: p:64, h:0, l:100000 (usec) | 657940.00 | (I) 9.05% | | | fix_size_alloc_test: p:64, h:1, l:100000 (usec) | 765422.00 | (I) 38.45% | | | fix_size_alloc_test: p:256, h:0, l:100000 (usec) | 2468585.00 | (I) 12.56% | | | fix_size_alloc_test: p:256, h:1, l:100000 (usec) | 2815758.33 | (I) 38.61% | | | fix_size_alloc_test: p:512, h:0, l:100000 (usec) | 4851969.00 | (I) 13.43% | | | fix_size_alloc_test: p:512, h:1, l:100000 (usec) | 4496257.33 | (I) 49.21% | | | full_fit_alloc_test: p:1, h:0, l:500000 (usec) | 570605.00 | -8.47% | | | kvfree_rcu_1_arg_vmalloc_test: p:1, h:0, l:500000 (usec) | 500866.00 | -8.17% | | | kvfree_rcu_2_arg_vmalloc_test: p:1, h:0, l:500000 (usec) | 499733.00 | -5.54% | | | long_busy_list_alloc_test: p:1, h:0, l:500000 (usec) | 5266237.67 | (I) 4.63% | | | pcpu_alloc_test: p:1, h:0, l:500000 (usec) | 490284.00 | 1.53% | | | random_size_align_alloc_test: p:1, h:0, l:500000 (usec) | 850986.33 | -0.00% | | | random_size_alloc_test: p:1, h:0, l:500000 (usec) | 2712106.00 | 1.22% | | | vm_map_ram_test: p:1, h:0, l:500000 (usec) | 111151.33 | (I) 4.98% | +-----------------+----------------------------------------------------------+-------------------+--------------+ mm-new vs vmalloc_2 results are in 2/3 patch. So this series is mitigating the regression on average as results show -14% to 49% improvement. Thanks, Muhammad Usama Anjum --- Changes since v4: (summary) - Patch 1: move can_free initialization inside the loop - Patch 1: Use pfn_to_page() for each pfn instead of page++ - Patch 2: Use num_pages_contiguous() instead of raw loop Chagnes since v3: (summary) - Introduce __free_contig_range_common() in first patch and use it in 3rd patch as well - Cosmetic changes related to comments and kerneldoc Changes since v2: (summary) - Patch 1 and 3: Rework the loop to check for memory sections - Patch 2: Rework by removing the BUG on and add helper free_pages_bulk() Changes since v1: - Update description - Rebase on mm-new and rerun benchmarks/tests - Patch 1: move FPI_PREPARED check and add todo - Patch 2: Rework catering newer changes in vfree() - New Patch 3: optimizes __free_contig_frozen_range() Muhammad Usama Anjum (1): mm/page_alloc: Optimize __free_contig_frozen_range() Ryan Roberts (2): mm/page_alloc: Optimize free_contig_range() vmalloc: Optimize vfree include/linux/gfp.h | 4 ++ mm/page_alloc.c | 141 ++++++++++++++++++++++++++++++++++++++++++-- mm/vmalloc.c | 16 ++--- 3 files changed, 144 insertions(+), 17 deletions(-) -- 2.47.3