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 CA5DBEB64D9 for ; Fri, 7 Jul 2023 09:40:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:From:References:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Cc:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Zsqqu3rkGCXTKSYeNzuyaJzMC2SLGhcp6TDjph9UIqA=; b=m0S+4djv3A8wgy as/+P+xqLfjCqbV/GnU7V68atOx0ExaLkrJEDLOeWa+t1WQXiWlk/H8es4On86WOzZV3w8YWL6KgT m297UdgFbTKZcqJVh0+JADD2/BUqF8HkT9hNjztrLMc/rG4FaJmILCrQ/XM2wfY6I2aqoeIbLM8N+ dMgKvAXvsbBqIazCorMxHJjyx++rS5MgvZAHO+bTnfKLrLc6Sdy2T5DxAuf3ulBwDXCTLN4Fy8lUN 55TtOHGTEFAMnaaSw8J2hMTo8QXxk9tKPg7QD/e8wC29epXm9fuMVktkZ0cMO3jwa7Lri2T3tM7u6 Lt2A4lcESQFi9wEeLjRw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qHhwS-0048rZ-05; Fri, 07 Jul 2023 09:39:56 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qHhwO-0048qf-2Z for linux-arm-kernel@lists.infradead.org; Fri, 07 Jul 2023 09:39:54 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9AB53D75 for ; Fri, 7 Jul 2023 02:40:27 -0700 (PDT) Received: from [10.57.77.63] (unknown [10.57.77.63]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 65C063F73F for ; Fri, 7 Jul 2023 02:39:45 -0700 (PDT) Message-ID: <6c496c30-0132-d335-e16b-44612a6b7792@arm.com> Date: Fri, 7 Jul 2023 10:39:43 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH v2 2/5] mm: Allow deferred splitting of arbitrary large anon folios To: linux-arm-kernel@lists.infradead.org References: <20230703135330.1865927-1-ryan.roberts@arm.com> <20230703135330.1865927-3-ryan.roberts@arm.com> <877crcgmj1.fsf@yhuang6-desk2.ccr.corp.intel.com> From: Ryan Roberts In-Reply-To: <877crcgmj1.fsf@yhuang6-desk2.ccr.corp.intel.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230707_023952_906688_9326083D X-CRM114-Status: GOOD ( 20.65 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 07/07/2023 09:21, Huang, Ying wrote: > Ryan Roberts writes: > >> With the introduction of large folios for anonymous memory, we would >> like to be able to split them when they have unmapped subpages, in order >> to free those unused pages under memory pressure. So remove the >> artificial requirement that the large folio needed to be at least >> PMD-sized. >> >> Signed-off-by: Ryan Roberts >> Reviewed-by: Yu Zhao >> Reviewed-by: Yin Fengwei >> --- >> mm/rmap.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/mm/rmap.c b/mm/rmap.c >> index 82ef5ba363d1..bbcb2308a1c5 100644 >> --- a/mm/rmap.c >> +++ b/mm/rmap.c >> @@ -1474,7 +1474,7 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma, >> * page of the folio is unmapped and at least one page >> * is still mapped. >> */ >> - if (folio_test_pmd_mappable(folio) && folio_test_anon(folio)) >> + if (folio_test_large(folio) && folio_test_anon(folio)) >> if (!compound || nr < nr_pmdmapped) >> deferred_split_folio(folio); >> } > > One possible issue is that even for large folios mapped only in one > process, in zap_pte_range(), we will always call deferred_split_folio() > unnecessarily before freeing a large folio. Hi Huang, thanks for reviewing! I have a patch that solves this problem by determining a range of ptes covered by a single folio and doing a "batch zap". This prevents the need to add the folio to the deferred split queue, only to remove it again shortly afterwards. This reduces lock contention and I can measure a performance improvement for the kernel compilation benchmark. See [1]. However, I decided to remove it from this patch set on Yu Zhao's advice. We are aiming for the minimal patch set to start with and wanted to focus people on that. I intend to submit it separately later on. [1] https://lore.kernel.org/linux-mm/20230626171430.3167004-8-ryan.roberts@arm.com/ Thanks, Ryan > > Best Regards, > Huang, Ying > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel