From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7A2E71061B04 for ; Mon, 30 Mar 2026 14:38:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B5B4D6B00A5; Mon, 30 Mar 2026 10:38:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B334B6B00A6; Mon, 30 Mar 2026 10:38:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A21FA6B00A7; Mon, 30 Mar 2026 10:38:55 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 90A746B00A5 for ; Mon, 30 Mar 2026 10:38:55 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 446731407F1 for ; Mon, 30 Mar 2026 14:38:55 +0000 (UTC) X-FDA: 84602986230.14.2D0BD3F Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf29.hostedemail.com (Postfix) with ESMTP id 8AF2512000B for ; Mon, 30 Mar 2026 14:38:53 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=WbBhdo3T; spf=pass (imf29.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774881533; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=EzhSrELvkS6EdHXYD4ii5EkLO4SkEOW4vMbzXFfPuz4=; b=RS1vrJVvHfYF2zgmBymZtjHu+R3pjCp0eBdTlfHfiy67DnSNeVKOyJWk1b0eZky5BVrLuy oeJRkU7bQTgTgKvQI+gw60LKuumXXI6t4u47To6qkkZ/cuwceAhiINZ086sSOX9LGHWinx kYiEHenUopnHa0uN4ROTCUDM6UizLmI= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=WbBhdo3T; spf=pass (imf29.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774881533; a=rsa-sha256; cv=none; b=6wXF/3MzNAXYAJcnIHBEj5AjwlyPdZWWOlOnnD4HW1+BP1irhnjV62Itk3ZgQegLm6XwC2 QamxRblBvwbdp3AJsxWRsonPAKILdHbEXPddSAKvSwTvSCK9y2qZRjuehnV/jCpdDOXnf+ EDnKvEXNgvBKrrQiyI1vMSfA+N2rvlo= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id A00C0444F1; Mon, 30 Mar 2026 14:38:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A23E0C4CEF7; Mon, 30 Mar 2026 14:38:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774881532; bh=I+rybS26QbA/CWVyj7rYJDrSj5jkFXVL+QylIC4QFaQ=; h=Date:Subject:To:References:From:In-Reply-To:From; b=WbBhdo3TzUKG3gOPg/9iehVdD3VcXIHKHdkMjIaHQT1rWya4Mw8cVastwWfaiRa/p DKurw/bIvbH43yTwW2KsIeomTRuW+xNUZrXjHZj+iSi7PH8GQrotpoZQ8K5IpeZzP6 SAbWVmKKb76Y7Aw1eZCbHzJM5VS+0ieylB6xwOteSv0byjrKKm/pp6HJKe1uaQC6Q0 QFzjRUzGfszXg+XqgbOV9nezyCmsq+xD0kBTEp5kjxLmKf4vBSSlV94+sNRwWlP22M WhAWipsk/u8DkQURTKXyF4ARHJHX/76RdeFXzR6V704X1v3+clgLuw0RUT4gw7xDj+ 7+fN5UOdSgJMg== Message-ID: <82e4055c-2343-49ee-b772-d3f4d134f8d0@kernel.org> Date: Mon, 30 Mar 2026 16:38:47 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/3] vmalloc: Optimize vfree To: Muhammad Usama Anjum , Andrew Morton , Lorenzo Stoakes , "Liam R . 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 References: <20260327125720.2270651-1-usama.anjum@arm.com> <20260327125720.2270651-3-usama.anjum@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260327125720.2270651-3-usama.anjum@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: qkaiifp486rwj9hpyx9pq5upd11uz6ja X-Rspamd-Queue-Id: 8AF2512000B X-Rspamd-Server: rspam09 X-HE-Tag: 1774881533-532983 X-HE-Meta: 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 /YrgiLk8 m0nvMWlNYN5WJ9NNAe8U4mT/FvhsAdGSeWC2b Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/27/26 13:57, Muhammad Usama Anjum wrote: > From: Ryan Roberts > > Whenever vmalloc allocates high order pages (e.g. for a huge mapping) it > must immediately split_page() to order-0 so that it remains compatible > with users that want to access the underlying struct page. > Commit a06157804399 ("mm/vmalloc: request large order pages from buddy > allocator") recently made it much more likely for vmalloc to allocate > high order pages which are subsequently split to order-0. > > Unfortunately this had the side effect of causing performance > regressions for tight vmalloc/vfree loops (e.g. test_vmalloc.ko > benchmarks). See Closes: tag. This happens because the high order pages > must be gotten from the buddy but then because they are split to > order-0, when they are freed they are freed to the order-0 pcp. > Previously allocation was for order-0 pages so they were recycled from > the pcp. > > It would be preferable if when vmalloc allocates an (e.g.) order-3 page > that it also frees that order-3 page to the order-3 pcp, then the > regression could be removed. > > So let's do exactly that; update stats separately first as coalescing is > hard to do correctly without complexity. Use free_pages_bulk() which uses > the new __free_contig_range() API to batch-free contiguous ranges of pfns. > This not only removes the regression, but significantly improves > performance of vfree beyond the baseline. > > A selection of test_vmalloc benchmarks running on arm64 server class > system. mm-new is the baseline. Commit a06157804399 ("mm/vmalloc: request > large order pages from buddy allocator") was added in v6.19-rc1 where we > see regressions. Then with this change performance is much better. (>0 > is faster, <0 is slower, (R)/(I) = statistically significant > Regression/Improvement): > > +-----------------+----------------------------------------------------------+-------------------+--------------------+ > | Benchmark | Result Class | mm-new | this series | > +=================+==========================================================+===================+====================+ > | micromm/vmalloc | fix_align_alloc_test: p:1, h:0, l:500000 (usec) | 1331843.33 | (I) 67.17% | > | | fix_size_alloc_test: p:1, h:0, l:500000 (usec) | 415907.33 | -5.14% | > | | fix_size_alloc_test: p:4, h:0, l:500000 (usec) | 755448.00 | (I) 53.55% | > | | fix_size_alloc_test: p:16, h:0, l:500000 (usec) | 1591331.33 | (I) 57.26% | > | | fix_size_alloc_test: p:16, h:1, l:500000 (usec) | 1594345.67 | (I) 68.46% | > | | fix_size_alloc_test: p:64, h:0, l:100000 (usec) | 1071826.00 | (I) 79.27% | > | | fix_size_alloc_test: p:64, h:1, l:100000 (usec) | 1018385.00 | (I) 84.17% | > | | fix_size_alloc_test: p:256, h:0, l:100000 (usec) | 3970899.67 | (I) 77.01% | > | | fix_size_alloc_test: p:256, h:1, l:100000 (usec) | 3821788.67 | (I) 89.44% | > | | fix_size_alloc_test: p:512, h:0, l:100000 (usec) | 7795968.00 | (I) 82.67% | > | | fix_size_alloc_test: p:512, h:1, l:100000 (usec) | 6530169.67 | (I) 118.09% | > | | full_fit_alloc_test: p:1, h:0, l:500000 (usec) | 626808.33 | -0.98% | > | | kvfree_rcu_1_arg_vmalloc_test: p:1, h:0, l:500000 (usec) | 532145.67 | -1.68% | > | | kvfree_rcu_2_arg_vmalloc_test: p:1, h:0, l:500000 (usec) | 537032.67 | -0.96% | > | | long_busy_list_alloc_test: p:1, h:0, l:500000 (usec) | 8805069.00 | (I) 74.58% | > | | pcpu_alloc_test: p:1, h:0, l:500000 (usec) | 500824.67 | 4.35% | > | | random_size_align_alloc_test: p:1, h:0, l:500000 (usec) | 1637554.67 | (I) 76.99% | > | | random_size_alloc_test: p:1, h:0, l:500000 (usec) | 4556288.67 | (I) 72.23% | > | | vm_map_ram_test: p:1, h:0, l:500000 (usec) | 107371.00 | -0.70% | > +-----------------+----------------------------------------------------------+-------------------+--------------------+ > > Fixes: a06157804399 ("mm/vmalloc: request large order pages from buddy allocator") > Closes: https://lore.kernel.org/all/66919a28-bc81-49c9-b68f-dd7c73395a0d@arm.com/ > Acked-by: Zi Yan > Signed-off-by: Ryan Roberts > Co-developed-by: Muhammad Usama Anjum > Signed-off-by: Muhammad Usama Anjum > --- > Changes since v3: > - Add kerneldoc comment and update description > - Add tag > > Changes since v2: > - Remove BUG_ON in favour of simple implementation as this has never > been seen to output any bug in the past as well > - Move the free loop to separate function, free_pages_bulk() > - Update stats, lruvec_stat in separate loop > > Changes since v1: > - Rebase on mm-new > - Rerun benchmarks > --- > include/linux/gfp.h | 2 ++ > mm/page_alloc.c | 38 ++++++++++++++++++++++++++++++++++++++ > mm/vmalloc.c | 16 +++++----------- > 3 files changed, 45 insertions(+), 11 deletions(-) > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index 7c1f9da7c8e56..71f9097ab99a0 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -239,6 +239,8 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid, > struct page **page_array); > #define __alloc_pages_bulk(...) alloc_hooks(alloc_pages_bulk_noprof(__VA_ARGS__)) > > +void free_pages_bulk(struct page **page_array, unsigned long nr_pages); > + > unsigned long alloc_pages_bulk_mempolicy_noprof(gfp_t gfp, > unsigned long nr_pages, > struct page **page_array); > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 18a96b51aa0be..64be8a9019dca 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -5175,6 +5175,44 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid, > } > EXPORT_SYMBOL_GPL(alloc_pages_bulk_noprof); > > +/* > + * free_pages_bulk - Free an array of order-0 pages > + * @page_array: Array of pages to free > + * @nr_pages: The number of pages in the array > + * > + * Free the order-0 pages. Adjacent entries whose PFNs form a contiguous > + * run are released with a single __free_contig_range() call. > + * > + * This assumes page_array is sorted in ascending PFN order. Without that, > + * the function still frees all pages, but contiguous runs may not be > + * detected and the freeing pattern can degrade to freeing one page at a > + * time. > + * > + * Context: Sleepable process context only; calls cond_resched() > + */ > +void free_pages_bulk(struct page **page_array, unsigned long nr_pages) > +{ > + unsigned long start_pfn = 0, pfn; > + unsigned long i, nr_contig = 0; > + > + for (i = 0; i < nr_pages; i++) { > + pfn = page_to_pfn(page_array[i]); > + if (!nr_contig) { > + start_pfn = pfn; > + nr_contig = 1; > + } else if (start_pfn + nr_contig != pfn) { > + __free_contig_range(start_pfn, nr_contig); > + start_pfn = pfn; > + nr_contig = 1; > + cond_resched(); > + } else { > + nr_contig++; > + } > + } What happened to the idea of using num_pages_contiguous()? I think that should generate more efficient code (all we're doing is comparing pointers really on SPARSEMEM_VMEMMAP) and the end result looks more readable? -- Cheers, David