From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lf1-f46.google.com (mail-lf1-f46.google.com [209.85.167.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3B2F139A04B for ; Wed, 25 Mar 2026 08:56:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774428968; cv=none; b=GWvasx42JWUbojbuv4ChBwmeCP/Bo+Wu5PrRw3WMj/CBm+CgQVlXIb3GMeG/oGcUdRyYoZ165AM5QwYNkGNRyLQpKWbfKKIRG4QYGCGgpxa87scOxBRR+KdDNN9f9mmcUbzSjEQAI6UU+8AALmzaN8I30GR1aTZnBmTfbBf3KIk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774428968; c=relaxed/simple; bh=bDEeZBZOAWwz1EVJgLMs5u70hrEdSx3ygSTWVHKvYJM=; h=From:Date:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=L4wKumwBBd7CpKulPPvDrBmn1GuegSDglnWQ7kSwtcZkii+fg4utdG+T/DERahVKdJVQ8mm8/C7L7Fi8S/vcZqZ0Y9L4GKPeEjme70GDtBHJoB8PqZ+vD9p9GgwR9D9zPZBptLTvACztv9kfLt+NbtklS1NLD6Xjvc+nGtV1W5g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=La9Dpobr; arc=none smtp.client-ip=209.85.167.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="La9Dpobr" Received: by mail-lf1-f46.google.com with SMTP id 2adb3069b0e04-5a27daa652fso6393657e87.0 for ; Wed, 25 Mar 2026 01:56:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1774428964; x=1775033764; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:from:to:cc:subject:date:message-id:reply-to; bh=PP9ZaWjF4kkscfMWl4N5NvAvTpHMI/CLS4RpQGDbPQE=; b=La9DpobrlEi7yJKEifwu9shvOIfMoZUb+La8G+BYN6n2X6DYWWaVZfeAkgkHU+Yo1t x1/vPLr0kX1BlXaopgCixVGVWmATBn3laqLlkTXoaCt3EzYIoEXFbBfNnGp7/hUjzcjt yEvZjAU+oXEDZ2LlCr/t1jprdfmOdBcHbpdFoHIsv9UjqoWc7x73zly4LHsOFx0r+uqi pFc2jXeXFr6ZKfmUCJT+ILZojbKPfSzJpuuOSgHcGzktTLGSCRrlxp1fkSahszDFwXi+ ALOowkNQ/Jtb6DYk7YjQZmt9PwR9JyK+oUdpJFz2YcwNrCe/k0wQUR4T9Fq2DQUw8YsK ePxw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774428964; x=1775033764; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=PP9ZaWjF4kkscfMWl4N5NvAvTpHMI/CLS4RpQGDbPQE=; b=OUvbXAvS/O/Mj1gNyMGBtskdmiaoF4cke59CDvs9hYUkdV7eGV76Jkg2aa21ndAjRJ +f+DTUNaNGshN9bLVJ9oGJa2AWavLLurymG4Ac3T50gI2H9Iqp2ftfOehPr6EAP/CENd qouyfC846f1el3cCHdn/lcUhptpVL3jJw4N5eoJ57TWjBXYtFSnWbu001lG5W64mXlwT Ng+21vIoVK/8M4ZlRyNECNwvBKZ6wDotD6SJpNwv4VkIMXaMG9UgSykOgmDc4bInymzY Q3r7C8FOd1x8M/BwD3QAVrXiBwwSEFljeCDatG4azkubFGEVIE6i8MBcRMh+g7RT7uoN bQ8w== X-Forwarded-Encrypted: i=1; AJvYcCXE7k17mZLejkxIr3HKhXGguURSv6uRpjDiXsWhWqfFo4YSnNYo0J9/UTDuKVoALjOCtog=@vger.kernel.org X-Gm-Message-State: AOJu0YygHn+EuUsEaOSV83z93TO+GIOuFt2kiP+o5TfMT81KhYkThdtl sJ2ZC2XOdaJHcC3gFo7ZbRMB922DfWCT8hJVFmlpWDNe1heIwrWsp0q8 X-Gm-Gg: ATEYQzxKDofaT9lFXD2MTmqA8/QEyWmIDRJ+Z64HZxDUWFkVEOCa65djWHhYiJok7W9 Qv9bosY5sm5NtojuigmQMEKeZgMYbyGmzMsDUGMgrCHP/u43M2C5THtq7Y0oxQEqHchzQjy4SHH K4KCPjNT0ffC4Xe9SATZ/aLFSGE3iXdfKOl/BYQwFZAuLVXSjNaTtViDXRwj1ig2Qn3EtYO6Jyb WBzmrrtt3U49vbYiHku8xywL5D0/ZcJwBlIZAAmnl/YbyK0jdDzfgDayO8FKFtrRQYaxDcfYSdS 2fXLBee367L56tV4iAobtVSntJd06WZh9KTWl8kOP1Gn7TbVxQsCZj0g/PMnKKtAda5DbcUJdC7 CtwBSjkl4+IejAJvUDyLpN83tJjMEwNB7JToZ6i/gxPjamy9wkjR9g+T7tuyGZQwL X-Received: by 2002:a05:6512:6181:b0:5a2:7b43:62da with SMTP id 2adb3069b0e04-5a29b992dabmr963125e87.30.1774428963937; Wed, 25 Mar 2026 01:56:03 -0700 (PDT) Received: from milan ([2001:9b1:d5a0:a500::24b]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5a285192b44sm3673978e87.5.2026.03.25.01.56.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Mar 2026 01:56:03 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Wed, 25 Mar 2026 09:56:01 +0100 To: Zi Yan Cc: Muhammad Usama Anjum , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , 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 Subject: Re: [PATCH v3 2/3] vmalloc: Optimize vfree Message-ID: References: <20260324133538.497616-1-usama.anjum@arm.com> <20260324133538.497616-3-usama.anjum@arm.com> <1D88CFF0-8A74-413F-9A6A-39E27B760AE1@nvidia.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1D88CFF0-8A74-413F-9A6A-39E27B760AE1@nvidia.com> On Tue, Mar 24, 2026 at 10:55:55AM -0400, Zi Yan wrote: > On 24 Mar 2026, at 9:35, 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; use 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/ > > Signed-off-by: Ryan Roberts > > Co-developed-by: Muhammad Usama Anjum > > Signed-off-by: Muhammad Usama Anjum > > --- > > 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 > > > > Made-with: Cursor > > --- > > include/linux/gfp.h | 2 ++ > > mm/page_alloc.c | 23 +++++++++++++++++++++++ > > mm/vmalloc.c | 16 +++++----------- > > 3 files changed, 30 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 eedce9a30eb7e..250cc07e547b8 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -5175,6 +5175,29 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid, > > } > > EXPORT_SYMBOL_GPL(alloc_pages_bulk_noprof); > > > > +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(); > It will cause schedule while atomic. Have you checked that __free_contig_range() also can sleep? Of so then we are aligned, if not probably we should remove it. -- Uladzislau Rezki