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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7542AEB64DA for ; Tue, 11 Jul 2023 01:58:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230419AbjGKB6l (ORCPT ); Mon, 10 Jul 2023 21:58:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53854 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230218AbjGKB6i (ORCPT ); Mon, 10 Jul 2023 21:58:38 -0400 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D501198 for ; Mon, 10 Jul 2023 18:58:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1689040717; x=1720576717; h=from:to:cc:subject:references:date:in-reply-to: message-id:mime-version; bh=mUJWbkk0R2FjZZFMtx9TSK7WG+4KdrbXbU/pwTbFtaE=; b=NAgE3uaiDZu99rEdpI2MGrDN97zMhjhAOBI5xXrhsYcaaqslAHVnhMpk tlM2puAh9Kuk+gQGCC9E9vaZ0hMiLrZGEc5ZYNdloZ0QqYMVly5RlZNU+ 0zh0RbnokIckj1ayKPJ4R+9Dl1KFqw6iET4YsZpd3MCJYK4otb6Gxy16u t/YZrQdrlVhPRUNB4q9U2QFdCgfHjXI97G0aFFOWpfpz6eXEBzVB/jXJN QU9S8COpOKO4HqTEdvfkxVLIUYy5jBSN2HXftRTUbdmmudAk3xftBDINZ o/9bt6hfDpZgXG8+NIh57RZmd9DPkTZpkOSfGeIsj/FSXmo0OtsWOf4kC w==; X-IronPort-AV: E=McAfee;i="6600,9927,10767"; a="349306988" X-IronPort-AV: E=Sophos;i="6.01,195,1684825200"; d="scan'208";a="349306988" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Jul 2023 18:58:37 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10767"; a="756178434" X-IronPort-AV: E=Sophos;i="6.01,195,1684825200"; d="scan'208";a="756178434" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Jul 2023 18:58:33 -0700 From: "Huang, Ying" To: Ryan Roberts Cc: Andrew Morton , Matthew Wilcox , "Kirill A. Shutemov" , Yin Fengwei , "David Hildenbrand" , Yu Zhao , "Catalin Marinas" , Will Deacon , "Anshuman Khandual" , Yang Shi , , , Subject: Re: [PATCH v2 2/5] mm: Allow deferred splitting of arbitrary large anon folios References: <20230703135330.1865927-1-ryan.roberts@arm.com> <20230703135330.1865927-3-ryan.roberts@arm.com> <877crcgmj1.fsf@yhuang6-desk2.ccr.corp.intel.com> <6379dd13-551e-3c73-422a-56ce40b27deb@arm.com> <87ttucfht7.fsf@yhuang6-desk2.ccr.corp.intel.com> <878rbof8cs.fsf@yhuang6-desk2.ccr.corp.intel.com> Date: Tue, 11 Jul 2023 09:56:56 +0800 In-Reply-To: (Ryan Roberts's message of "Mon, 10 Jul 2023 10:39:58 +0100") Message-ID: <87r0pfdxcn.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ryan Roberts writes: > On 10/07/2023 10:01, Huang, Ying wrote: >> Ryan Roberts writes: >> >>> On 10/07/2023 06:37, Huang, Ying wrote: >>>> Ryan Roberts writes: >>>> >>>>> Somehow I managed to reply only to the linux-arm-kernel list on first attempt so >>>>> resending: >>>>> >>>>> 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 for your information! "batch zap" can solve the problem. >>>> >>>> And, I agree with Matthew's comments to fix the large folios interaction >>>> issues before merging the patches to allocate large folios as in the >>>> following email. >>>> >>>> https://lore.kernel.org/linux-mm/ZKVdUDuwNWDUCWc5@casper.infradead.org/ >>>> >>>> If so, we don't need to introduce the above problem or a large patchset. >>> >>> I appreciate Matthew's and others position about not wanting to merge a minimal >>> implementation while there are some fundamental features (e.g. compaction) it >>> doesn't play well with - I'm working to create a definitive list so these items >>> can be tracked and tackled. >> >> Good to know this, Thanks! >> >>> That said, I don't see this "batch zap" patch as an example of this. It's just a >>> performance enhancement that improves things even further than large anon folios >>> on their own. I'd rather concentrate on the core changes first then deal with >>> this type of thing later. Does that work for you? >> >> IIUC, allocating large folios upon page fault depends on splitting large >> folios in page_remove_rmap() to avoid memory wastage. Splitting large >> folios in page_remove_rmap() depends on "batch zap" to avoid performance >> regression in zap_pte_range(). So we need them to be done earlier. Or >> I miss something? > > My point was just that large anon folios improves performance significantly > overall, despite a small perf regression in zap_pte_range(). That regression is > reduced further by a patch from Yin Fengwei to reduce the lock contention [1]. > So it doesn't seem urgent to me to get the "batch zap" change in. I don't think Fengwei's patch will help much here. Because that patch is to optimize if the folio isn't in deferred split queue, but now the folio will be put in deferred split queue. And I don't think allocating large folios upon page fault is more urgent. We should avoid regression if possible. > I'll add it to my list, then prioritize it against the other stuff. > > [1] https://lore.kernel.org/linux-mm/20230429082759.1600796-1-fengwei.yin@intel.com/ > Best Regards, Huang, Ying 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 9C84EEB64D9 for ; Tue, 11 Jul 2023 01:59:16 +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:MIME-Version:Message-ID:In-Reply-To: Date:References:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=xOgTTJ61v7TyFdWoONiyf166EuRMJwvkPUBP21YV53k=; b=QeUH5Py+NYimuD ++LyrHzA2RD70xgdurTeTFh8gfSx+oIV7tHGK1HMjWGdae2J9oo/icm/epLC6Koru/bMWTerqnhzQ K8rhfh2C72iS40uMPu3UquxFcIXxxt/Yfsf4aABCa8Vea6f7bV3yakuGeqrf7LiVLopwsTnMgz8mn RJfbuM3AcpdX2xx4hRjTe4aiIX0+LZw/zNJYg/6ygTQUVHNvqREB/VqerqxDtGFasMGgTIuLkieCH 5tXaz6XP+rTaO7xENX/MdwFQfhU+i+hpXjfSfqZ0WbWJEsD92FWvhMCVkr5PyjEnHqotfufL+dQ84 aP0VEqZefBq7fgXdEuyA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qJ2eI-00DFiG-1r; Tue, 11 Jul 2023 01:58:42 +0000 Received: from mga18.intel.com ([134.134.136.126]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qJ2eF-00DFgf-0D for linux-arm-kernel@lists.infradead.org; Tue, 11 Jul 2023 01:58:40 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1689040719; x=1720576719; h=from:to:cc:subject:references:date:in-reply-to: message-id:mime-version; bh=mUJWbkk0R2FjZZFMtx9TSK7WG+4KdrbXbU/pwTbFtaE=; b=BFoaV74x5UQYSnZWGueJd/3nB6Uoh3XH7+neSp1ygCdVAj7NuXPexEkt 9DPlm6rYUFVnANoweUYiU/edr+3LCRbUBDXxQh22NNd5mj+8h7SMeqJan oRLn0TfhlmmSBz85FL9k81lBXqRgzwddXupzJMfwcUIzL/r8wAIiSjrc7 83JTmQ1WMiQbrNa9pfDb3EGlGDBlvmTGOLAHjH3tW/t0RDUrG7pRggTWA 8++qBNWt0kPGa1Tmc+lqZdbO3O48Eup0ck76M92c4IQcGj/NpPTSkcRjB PhJ2BdHKCQ6plnNjoYi/PT21EdCBl+gZqpB6stb48bnYlBEwZC0Mz1UXn w==; X-IronPort-AV: E=McAfee;i="6600,9927,10767"; a="349306991" X-IronPort-AV: E=Sophos;i="6.01,195,1684825200"; d="scan'208";a="349306991" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Jul 2023 18:58:37 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10767"; a="756178434" X-IronPort-AV: E=Sophos;i="6.01,195,1684825200"; d="scan'208";a="756178434" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Jul 2023 18:58:33 -0700 From: "Huang, Ying" To: Ryan Roberts Cc: Andrew Morton , Matthew Wilcox , "Kirill A. Shutemov" , Yin Fengwei , "David Hildenbrand" , Yu Zhao , "Catalin Marinas" , Will Deacon , "Anshuman Khandual" , Yang Shi , , , Subject: Re: [PATCH v2 2/5] mm: Allow deferred splitting of arbitrary large anon folios References: <20230703135330.1865927-1-ryan.roberts@arm.com> <20230703135330.1865927-3-ryan.roberts@arm.com> <877crcgmj1.fsf@yhuang6-desk2.ccr.corp.intel.com> <6379dd13-551e-3c73-422a-56ce40b27deb@arm.com> <87ttucfht7.fsf@yhuang6-desk2.ccr.corp.intel.com> <878rbof8cs.fsf@yhuang6-desk2.ccr.corp.intel.com> Date: Tue, 11 Jul 2023 09:56:56 +0800 In-Reply-To: (Ryan Roberts's message of "Mon, 10 Jul 2023 10:39:58 +0100") Message-ID: <87r0pfdxcn.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230710_185839_229103_BCC85BFA X-CRM114-Status: GOOD ( 32.79 ) 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 Ryan Roberts writes: > On 10/07/2023 10:01, Huang, Ying wrote: >> Ryan Roberts writes: >> >>> On 10/07/2023 06:37, Huang, Ying wrote: >>>> Ryan Roberts writes: >>>> >>>>> Somehow I managed to reply only to the linux-arm-kernel list on first attempt so >>>>> resending: >>>>> >>>>> 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 for your information! "batch zap" can solve the problem. >>>> >>>> And, I agree with Matthew's comments to fix the large folios interaction >>>> issues before merging the patches to allocate large folios as in the >>>> following email. >>>> >>>> https://lore.kernel.org/linux-mm/ZKVdUDuwNWDUCWc5@casper.infradead.org/ >>>> >>>> If so, we don't need to introduce the above problem or a large patchset. >>> >>> I appreciate Matthew's and others position about not wanting to merge a minimal >>> implementation while there are some fundamental features (e.g. compaction) it >>> doesn't play well with - I'm working to create a definitive list so these items >>> can be tracked and tackled. >> >> Good to know this, Thanks! >> >>> That said, I don't see this "batch zap" patch as an example of this. It's just a >>> performance enhancement that improves things even further than large anon folios >>> on their own. I'd rather concentrate on the core changes first then deal with >>> this type of thing later. Does that work for you? >> >> IIUC, allocating large folios upon page fault depends on splitting large >> folios in page_remove_rmap() to avoid memory wastage. Splitting large >> folios in page_remove_rmap() depends on "batch zap" to avoid performance >> regression in zap_pte_range(). So we need them to be done earlier. Or >> I miss something? > > My point was just that large anon folios improves performance significantly > overall, despite a small perf regression in zap_pte_range(). That regression is > reduced further by a patch from Yin Fengwei to reduce the lock contention [1]. > So it doesn't seem urgent to me to get the "batch zap" change in. I don't think Fengwei's patch will help much here. Because that patch is to optimize if the folio isn't in deferred split queue, but now the folio will be put in deferred split queue. And I don't think allocating large folios upon page fault is more urgent. We should avoid regression if possible. > I'll add it to my list, then prioritize it against the other stuff. > > [1] https://lore.kernel.org/linux-mm/20230429082759.1600796-1-fengwei.yin@intel.com/ > Best Regards, Huang, Ying _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel