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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A9C8ED5B87C for ; Tue, 16 Dec 2025 05:49:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=tRhxoTZ+3IIdYwTnJoWC2Y2iVLI35ww6bqSlIUl0XxQ=; b=NCAApA8K9Pys5p8mrykVje7cOJ mAiY9GWadjwrUiDx/bBiRSYzK1tM0h2YgQt58KHVR/I3a3Axvc/g2PtMscfYBQ4REuCJBlT8Aq5R1 ikYEHF90hA+/tDBOIqhONRhkLTKqhcBaGrliWz9eEa6Jhmu5f4rHAp36le7PLYfIOvxM48shCUS/Z d3A7vHCEpQ51j5JOy6MIThqQjseu9Y5bGDepbBFS/BVsj9WIKyU4OQceKUzh2ENquHK3dj+gBM+9U zd/nAf3/J9aNJsQGFpM+juDCJhB2WDmNf57Q87YkW2/4Jshy9h/tT00OevDw/GfxDy34rilrsM9Ln 1A7H0MUA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vVNvh-00000004jHb-2KbU; Tue, 16 Dec 2025 05:49:01 +0000 Received: from out30-132.freemail.mail.aliyun.com ([115.124.30.132]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vVNve-00000004jGj-3uyl for linux-arm-kernel@lists.infradead.org; Tue, 16 Dec 2025 05:49:00 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1765864136; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=tRhxoTZ+3IIdYwTnJoWC2Y2iVLI35ww6bqSlIUl0XxQ=; b=ley2j58OCPEN3x20n8oxg6pFGJnGlk8GrMo6CL7d8+SvNvePqBKLUq2zNhA69T4xehYYRq+rk92Sb5AO9y9kgdahimDadEQI3sKh+agUOHv59vqzALUkG+xmRYVzLfABQHgGGMmxtztC3YRqcbWinHXYjt1b+HgXMU/N+v/YZE8= Received: from 30.74.144.116(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Wuxvaan_1765864133 cluster:ay36) by smtp.aliyun-inc.com; Tue, 16 Dec 2025 13:48:53 +0800 Message-ID: Date: Tue, 16 Dec 2025 13:48:52 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/3] mm: rmap: support batched unmapping for file large folios To: Lorenzo Stoakes Cc: akpm@linux-foundation.org, david@kernel.org, catalin.marinas@arm.com, will@kernel.org, ryan.roberts@arm.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, riel@surriel.com, harry.yoo@oracle.com, jannh@google.com, willy@infradead.org, baohua@kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <70d1dedc-b4fc-4eb6-baf6-9e54b6a62249@lucifer.local> From: Baolin Wang In-Reply-To: <70d1dedc-b4fc-4eb6-baf6-9e54b6a62249@lucifer.local> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251215_214859_126380_B0F4B040 X-CRM114-Status: GOOD ( 19.02 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2025/12/15 20:38, Lorenzo Stoakes wrote: > On Thu, Dec 11, 2025 at 04:16:56PM +0800, Baolin Wang wrote: >> Similar to folio_referenced_one(), we can apply batched unmapping for file >> large folios to optimize the performance of file folios reclamation. >> >> Performance testing: >> Allocate 10G clean file-backed folios by mmap() in a memory cgroup, and try to >> reclaim 8G file-backed folios via the memory.reclaim interface. I can observe >> 75% performance improvement on my Arm64 32-core server. > > Again, you must test on non-arm64 architectures and report the numbers for this > also. Yes, I've tested on the x86 machine, and will add the data in the commit message. >> W/o patch: >> real 0m1.018s >> user 0m0.000s >> sys 0m1.018s >> >> W/ patch: >> real 0m0.249s >> user 0m0.000s >> sys 0m0.249s >> >> Signed-off-by: Baolin Wang >> --- >> mm/rmap.c | 7 ++++--- >> 1 file changed, 4 insertions(+), 3 deletions(-) >> >> diff --git a/mm/rmap.c b/mm/rmap.c >> index ec232165c47d..4c9d5777c8da 100644 >> --- a/mm/rmap.c >> +++ b/mm/rmap.c >> @@ -1855,9 +1855,10 @@ static inline unsigned int folio_unmap_pte_batch(struct folio *folio, >> end_addr = pmd_addr_end(addr, vma->vm_end); >> max_nr = (end_addr - addr) >> PAGE_SHIFT; >> >> - /* We only support lazyfree batching for now ... */ >> - if (!folio_test_anon(folio) || folio_test_swapbacked(folio)) >> + /* We only support lazyfree or file folios batching for now ... */ >> + if (folio_test_anon(folio) && folio_test_swapbacked(folio)) > > Why is it now ok to support file-backed batched unmapping when it wasn't in > Barry's series (see [0])? You don't seem to be justifying this? Barry's series[0] is merely aimed at optimizing lazyfree anonymous large folios and does not continue to optimize anonymous large folios or file-backed large folios at that point. Subsequently, Barry sent out a new patch (see [1]) to optimize anonymous large folios. As for file-backed large folios, the batched unmapping support is relatively simple, since we only need to clear the PTE entries for file-backed large folios. > [0]:https://lore.kernel.org/all/20250214093015.51024-4-21cnbao@gmail.com/T/#u [1] https://lore.kernel.org/all/20250513084620.58231-1-21cnbao@gmail.com/ >> return 1; >> + >> if (pte_unused(pte)) >> return 1; >> >> @@ -2223,7 +2224,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, >> * >> * See Documentation/mm/mmu_notifier.rst >> */ >> - dec_mm_counter(mm, mm_counter_file(folio)); >> + add_mm_counter(mm, mm_counter_file(folio), -nr_pages); > > Was this just a bug before? Nope. Before this patch, we never supported batched unmapping for file-backed large folios, so the 'nr_pages' was always 1. After this patch, we should use the number of pages in this file-backed large folio.