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 60538C4167B for ; Tue, 28 Nov 2023 20:43:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BFAAE6B034D; Tue, 28 Nov 2023 15:43:44 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BAAC26B034F; Tue, 28 Nov 2023 15:43:44 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A72296B0350; Tue, 28 Nov 2023 15:43:44 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 88E336B034D for ; Tue, 28 Nov 2023 15:43:44 -0500 (EST) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 5AFA9A03A1 for ; Tue, 28 Nov 2023 20:43:44 +0000 (UTC) X-FDA: 81508539168.19.200670E Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf11.hostedemail.com (Postfix) with ESMTP id 59C444000B for ; Tue, 28 Nov 2023 20:43:42 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=MXoOpnZe; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf11.hostedemail.com: domain of chrisl@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=chrisl@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1701204222; 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:dkim-signature; bh=zluw2DC70GYX/P7l0aEPrLembQ/h05W1n/NwO/xNCpM=; b=rTF5I65UZ3CMBwEeJ59mVvm5cPtYq+CCfvHceTM626oNAFYfaW8pVwTyl8NQGx7XVCyz7i NMRHG0/3y97x0l9F+dR7poz4QpzD0ZIIqzwWf/tP3b/1QvwogDnNQH2MG7pB3Ha3D5Maea qzffl2HZDTUhFsrg9lw4yP13iqOKFWk= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=MXoOpnZe; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf11.hostedemail.com: domain of chrisl@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=chrisl@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1701204222; a=rsa-sha256; cv=none; b=xTdPI/toEK6H0VSye+sRXNY8VejfXz8bUOrs+v8u1BCktjXqS70rWkVkidLntVcNuu+azO ur/OqakebpQsziH9XHAEoKH1tkh+ZSQVCDp/QLntrLFoxx91yiYVEHRmYRDVxdwbVmIxpl 7YlwZcRU1WZ00tb3f/lPjozw18XRNbw= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by ams.source.kernel.org (Postfix) with ESMTP id 4EACFB83C8F for ; Tue, 28 Nov 2023 20:43:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A3E44C433CB for ; Tue, 28 Nov 2023 20:43:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701204219; bh=dUgTGnBvyni9rwICv+SXPMmCh79rCf51zZBSe5UWymw=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=MXoOpnZevWjE8Ej+PcA0NUdIprGWk8COluDTOPxY5vvD/35dH7lL4yQgP+1a0epn3 cLv9EFzXR23yWIphtyB3KqIKX/ZlS/GyDAdwsDAXBcIojxUTX69fnl/eDYAtze4U8A s+LfUz6ZtYh5SZcnr/tX56VCz8KLToMZX72eFdlJUvhhqyB/nErRRnvZWFCYWWFlcQ Ouo3ODf6ueRK2mAVBgAukLt5Q7suXlaFQfqzWY4UrGJcDaNNNjejSulWeOO0RmSXO/ D2HM2zwhMsmXSYiU5bIC2vj8wOepDIGJAK9x3VQy4x9vy0GKZsx/y316mJ+wkKU9HI MDovjx3nfpfmw== Received: by mail-pl1-f182.google.com with SMTP id d9443c01a7336-1cf89df1eecso41878135ad.3 for ; Tue, 28 Nov 2023 12:43:39 -0800 (PST) X-Gm-Message-State: AOJu0YxE0SnYpSmMVr8iLvcfcB9j5wxHmdEgJtJB/Uac/NErbmuf+raV h3bwAk+NlUR2euyRCzDkE4zN5ircnaPcmyBQRcy7VQ== X-Google-Smtp-Source: AGHT+IHJ6RxMb0AXm3RZ0SOnfsUX8ufpGFi3Jf2EIhd4yB0xF73EZBYwC9oyT8DjnPg4hBkQ3xgcrxbI/yFzFsHtOok= X-Received: by 2002:a17:90b:3946:b0:285:be73:45ae with SMTP id oe6-20020a17090b394600b00285be7345aemr7679655pjb.49.1701204219017; Tue, 28 Nov 2023 12:43:39 -0800 (PST) MIME-Version: 1.0 References: <20231127160058.586446-1-fabio.maria.de.francesco@linux.intel.com> In-Reply-To: From: Chris Li Date: Tue, 28 Nov 2023 12:43:26 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] mm/zswap: Replace kmap_atomic() with kmap_local_page() To: Matthew Wilcox Cc: "Fabio M. De Francesco" , Seth Jennings , Dan Streetman , Vitaly Wool , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ira Weiny , Nhat Pham Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 59C444000B X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: h8qjep6ciq54u8ih8wisox4y93re8hj1 X-HE-Tag: 1701204222-706909 X-HE-Meta: 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 r0OcTgIP YUT0flpdH+HzmIQuoHDTMNanLZBVeBvwP9iYP9kEigGwBDij/Rxs5nk9dj+xkasDaYfGjLlHphJRAgt0Klw9ieUahmV1vyN64qGKdAlKX18gXi42LADzVNJuoRwAMZ+rSx+Ft6TBGdWYPH2xpAVE4S7mr46R3UTsnzx6yRsrheEibU2l2z/KerNLJ09lercHmLOl/FTIXzDv9hyOldWZSj+tJsVHIbGIIYaa/6DTIzKW8xfKep65y11eoB1i5gXkCtk8K6rMnbyOWoLxde7Y7x1ShPmTZcSeLY51DyTC9UQzUII2YReonaSZn0Qfq3657FybS0R+YoX+PdSvVt+I12EFK6ifbVh2K2J3F+WdjeD2twsGNQhB8t2NsHCODH/yg/nOB 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: Hi Matthew, On Tue, Nov 28, 2023 at 6:09=E2=80=AFAM Matthew Wilcox wrote: > > > > >From the performance perspective, kmap_local_page() does less so it > > has some performance gain. I am trying to think would it have another > > unwanted side effect of enabling interrupt and page fault while zswap > > decompressing a page. > > The decompression should not generate page fault. The interrupt > > enabling might introduce extra latency, but most of the page fault was > > having interrupt enabled anyway. The time spent in decompression is > > relatively small compared to the whole duration of the page fault. So > > the interrupt enabling during those short windows should be fine. > > "Should" is the famous last word. > > Interrupts are enabled with kmap_atomic() too. The difference is > whether we can be preempted by a higher-priority process. > You are right, thanks for the clarification. Hi Fabio, Acked-by: Chris Li (Google) Chris