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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39F21C67861 for ; Mon, 8 Apr 2024 09:32:05 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C5C9E6B0093; Mon, 8 Apr 2024 05:32:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C0D3B6B0095; Mon, 8 Apr 2024 05:32:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AFBFA6B009C; Mon, 8 Apr 2024 05:32:04 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 8C3DC6B0093 for ; Mon, 8 Apr 2024 05:32:04 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 40C3CA08F3 for ; Mon, 8 Apr 2024 09:32:04 +0000 (UTC) X-FDA: 81985848168.19.AD91FF3 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf19.hostedemail.com (Postfix) with ESMTP id 5036C1A0013 for ; Mon, 8 Apr 2024 09:32:02 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf19.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1712568722; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PdknYLekP+qvefYXJW8uumM1vtzOnGHgE7CgcO7PS0M=; b=hMolmjrd5EDx8XtAiEkU+PTwS3DNoucWCiqc68UBRrmY1ijkzQMoqJN3ZzF/VrlKfpyUi9 6ccrd5MBGYd2PkZTPlXq0fKD3JXMiW4oqlL+OwgnsQoBhzKZfziN7M1RQko3aTn1aoTh9j 49LAf9FtZRV4QWjwSQ7qJqBUeR+G8ws= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf19.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1712568722; a=rsa-sha256; cv=none; b=bLVJgwnmV7dGi28M4K7l+zmO5YBaWv6rF3BiTdlhBjWH+30mvlBMHOt/nCnp6d8HJxpr4z GBRZ5VgoK2uFT3zN/4vkxKyXUhIFz21BOm8v80nxNdl0D3vyADZ/ItjrtmOpA8pBXZXOLX IjVu5Je1KrgA62hoXG7u2UtQUkh9vZo= 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 CEB991007; Mon, 8 Apr 2024 02:32:31 -0700 (PDT) Received: from [10.57.73.169] (unknown [10.57.73.169]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 693B13F766; Mon, 8 Apr 2024 02:31:59 -0700 (PDT) Message-ID: <47eccc1b-71a2-43f3-8d44-7d26c6ddd4f0@arm.com> Date: Mon, 8 Apr 2024 10:31:58 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 5/6] mm: vmscan: Avoid split during shrink_folio_list() Content-Language: en-GB To: David Hildenbrand , Andrew Morton , Matthew Wilcox , Huang Ying , Gao Xiang , Yu Zhao , Yang Shi , Michal Hocko , Kefeng Wang , Barry Song <21cnbao@gmail.com>, Chris Li , Lance Yang Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Barry Song References: <20240403114032.1162100-1-ryan.roberts@arm.com> <20240403114032.1162100-6-ryan.roberts@arm.com> <6653ce52-53a2-4d91-b98f-50f1608ae59c@redhat.com> From: Ryan Roberts In-Reply-To: <6653ce52-53a2-4d91-b98f-50f1608ae59c@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 5036C1A0013 X-Stat-Signature: 8itwsghkfbgu16fxou45f54jy51fj8kh X-HE-Tag: 1712568722-202722 X-HE-Meta: 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 0ssX2z3/ I7wkdaDyuIBs9EyF+W/+bnl9yDW4FJtDyPHS5aEmhihARVkjPmOrdm8AV4x6e45D+RauCfnFYSY5gXNXAquW8v2QuN8/Ql0TaCNqNo6GdWtiToZGmKCbwu+r/YBjdT3OO4gxok6SvDMXi9ugGoTbi985FmS7dFmnsIMH0i1mMdLil51z/+CdyIZsqp+LJNjCXMrHywN8wueJamNE1Xk341YSTsMzKgKHWHVXYwFU9E6d/xpDvYaLIkY5CoERS3YBSIZoE6DOJA3W5JALEdOmdlcAXK+GnRkhqsfAitohzrtKv0oIngWRio9nMFyuF+FoOlbAxFV8wKSzb0bDHglDavvxzX+UU2zeqn82XS65sUCAsjEQ= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 05/04/2024 11:42, David Hildenbrand wrote: > On 03.04.24 13:40, Ryan Roberts wrote: >> Now that swap supports storing all mTHP sizes, avoid splitting large >> folios before swap-out. This benefits performance of the swap-out path >> by eliding split_folio_to_list(), which is expensive, and also sets us >> up for swapping in large folios in a future series. >> >> If the folio is partially mapped, we continue to split it since we want >> to avoid the extra IO overhead and storage of writing out pages >> uneccessarily. >> >> THP_SWPOUT and THP_SWPOUT_FALLBACK counters should continue to count >> events only for PMD-mappable folios to avoid user confusion. THP_SWPOUT >> already has the appropriate guard. Add a guard for THP_SWPOUT_FALLBACK. >> It may be appropriate to add per-size counters in future. >> >> Reviewed-by: David Hildenbrand >> Reviewed-by: Barry Song >> Signed-off-by: Ryan Roberts >> --- >>   mm/vmscan.c | 17 +++++++++++------ >>   1 file changed, 11 insertions(+), 6 deletions(-) >> >> diff --git a/mm/vmscan.c b/mm/vmscan.c >> index 00adaf1cb2c3..ffc4553c8615 100644 >> --- a/mm/vmscan.c >> +++ b/mm/vmscan.c >> @@ -1223,11 +1223,12 @@ static unsigned int shrink_folio_list(struct list_head >> *folio_list, >>                       if (!can_split_folio(folio, NULL)) >>                           goto activate_locked; >>                       /* >> -                     * Split folios without a PMD map right >> -                     * away. Chances are some or all of the >> -                     * tail pages can be freed without IO. >> +                     * Split partially mapped folios right >> +                     * away. We can free the unmapped pages >> +                     * without IO. >>                        */ >> -                    if (!folio_entire_mapcount(folio) && >> +                    if (data_race(!list_empty( >> +                        &folio->_deferred_list)) && > > Please violate the 80 chars rule where reasonable. > > " > Statements longer than 80 columns should be broken into sensible chunks, unless > exceeding 80 columns significantly increases readability and does not hide > information. > " > > > Likely some of that code here should be refactored into readable sub-functions. > > codingstyle also mentions > > "The answer to that is that if you need more than 3 levels of indentation, > you're screwed anyway, and should fix your program." > Boo! :) Yeah, no problem, I'll sort this.