From nobody Sat Nov 15 19:01:57 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1749486005; cv=none; d=zohomail.com; s=zohoarc; b=WbOhKulcrK5fjSkFI+23LPm8KENK4zQCh6lnr31Qos3giOw6RwiF7nEG9cFCITeBBvkFw2kAwXN/O1NQbexv0lODI4efVj7s/ENiiZRMX31ch/Mtj59oKq4W7Ph30F7zFuW49mJwCthMxFSCQ1dx/VsUxM9hXVwi27+4dzJPxnw= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1749486005; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=81vpRbPBsl4TxnkuqSVUCogqP7kEXR/iTLHp+dsYNmM=; b=PezOj4exwgotKhf/BQLzLxoilMhaJGv9FFxpFAjHMAhrKCJD5mtaOZSGPCI+irg0uE5J6aMpefQTJp4GAEtqOfW3x48AY8XTgcFdydkpWl7rCXo9pyKtw0KwB7O3RxX1/wYKiUkV6jM/jkYUPoL+vnoSu+268Aum0imJzTN8MTo= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1749486005198443.1748203800554; Mon, 9 Jun 2025 09:20:05 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uOfDU-0000O8-S2; Mon, 09 Jun 2025 12:19:20 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uOfDS-0000Jw-OY for qemu-devel@nongnu.org; Mon, 09 Jun 2025 12:19:18 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uOfDQ-0004VY-V2 for qemu-devel@nongnu.org; Mon, 09 Jun 2025 12:19:18 -0400 Received: from mail-qv1-f72.google.com (mail-qv1-f72.google.com [209.85.219.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-610-WrAZOdTUOQ6xog6OK0mAqA-1; Mon, 09 Jun 2025 12:19:15 -0400 Received: by mail-qv1-f72.google.com with SMTP id 6a1803df08f44-6faca0f2677so127365306d6.1 for ; Mon, 09 Jun 2025 09:19:15 -0700 (PDT) Received: from x1.local ([85.131.185.92]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6fb09ab95c1sm53420546d6.15.2025.06.09.09.19.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Jun 2025 09:19:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1749485956; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=81vpRbPBsl4TxnkuqSVUCogqP7kEXR/iTLHp+dsYNmM=; b=YhEGNd17w2Q4O8WnFbsgkG0KR6VJI7qrv5x+hPsqcXxutwSz9TVjf9vvG3cQJvb9T3v6Hz eI0ABkZao/dBQnHYtoTgXaFQHDzE8a+ak6Aq3tQCxp8/QaqujhdM9Vqhrgq3xXhd2XivLy +DPikUMQaqZLdXAOz+hPbpi+OCmxifE= X-MC-Unique: WrAZOdTUOQ6xog6OK0mAqA-1 X-Mimecast-MFC-AGG-ID: WrAZOdTUOQ6xog6OK0mAqA_1749485955 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1749485954; x=1750090754; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=81vpRbPBsl4TxnkuqSVUCogqP7kEXR/iTLHp+dsYNmM=; b=Pgz8BaZVufntzZ4voVjUWDvf2oxkIPHWel5Vb7yQwvTbejLLvw4+WAl2XZiH8StLFT RIJHGUDdOATy+HDmIvzR4H4L/zZfqxq37dUJpKYSzOEtmPY53gpfi2bFfRLlopI5HqsE fISxnNPno71F+crRsFP2UmDN/T0fpVm16xnsg9a1xHoU+ujPwEQHlskWPPg9xUIZKqRX m8jEsRT5MGVoHwIii3W3IwgZlnLT4ST5ctHTzqYeom9GA0/U2ORldjLC6YETtk7ZX5vj +PPJTKuCkB3AFqmVCKkQdlt7Vwuf0Wpg6MIiYcKGo2NErOIYpB0rXhB6MeM128d8Ub12 fnEw== X-Gm-Message-State: AOJu0Yw8T9F+9s8/7O3QTfwgpg9yKyEyETWWnVXbWau4Rd/mgtyRAH9a WFru/t5zwyYJl6cOsCkONntLdyktiTgQbzTrE8IGFYCnwjdrZmEh5ZA+wWgLrfSe1gtb0L6qUU+ LXGZSttivXQkVi9WwKqqfHWW17W4YmlQGuUJOR9CvuLesfWr6GGBoPEF/g2cVenoymGEll87zNd E9CXo1sAfi8p1l/qH1/uXKPyzvAEajtI2Tu9+kwA== X-Gm-Gg: ASbGncunbd5SlcNT/rWoIA61qV1BrNvBdozoIpOWwsie0X3HuSmu6h9zD69iVLr5fRU mVFthWoIVA900AL18b6dcMYGWJUqsSY1wLB6m4bX6k5F/6f0XC2K/ha9qlNOsfWCNUqFDVLNvIF WqPCN34VcbwnwS/+N8SVL8iWn8UNMUbD9bgRP1XuLE6zVUnDCpBEdWQCkNnGGnSfUnvb2JnxltI eBUOtYv6hOmZmZGFdLpe8YMnZr4EHMMhfHV54h1e9oMWHhfgLpzIAZY4h7t1i6C3A5/X3KUX5ox NV4= X-Received: by 2002:a05:6214:528d:b0:6fa:bab1:f797 with SMTP id 6a1803df08f44-6fb08fe4c73mr220722506d6.10.1749485954447; Mon, 09 Jun 2025 09:19:14 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGZErq1RkJKPnlNKJLCLF5JDlQ1gErGbxsBDnSZAz9cCLB4pVASt1u/61YVXtUWWCw0j8lZhw== X-Received: by 2002:a05:6214:528d:b0:6fa:bab1:f797 with SMTP id 6a1803df08f44-6fb08fe4c73mr220722006d6.10.1749485953970; Mon, 09 Jun 2025 09:19:13 -0700 (PDT) From: Peter Xu To: qemu-devel@nongnu.org Cc: Juraj Marcin , peterx@redhat.com, "Dr . David Alan Gilbert" , Fabiano Rosas , Yanfei Xu Subject: [PATCH v2 11/11] migration/postcopy: Avoid clearing dirty bitmap for postcopy too Date: Mon, 9 Jun 2025 12:18:55 -0400 Message-ID: <20250609161855.6603-12-peterx@redhat.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250609161855.6603-1-peterx@redhat.com> References: <20250609161855.6603-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1749486006882116600 Content-Type: text/plain; charset="utf-8" This is a follow up on the other commit "migration/ram: avoid to do log clear in the last round" but for postcopy. https://lore.kernel.org/r/20250514115827.3216082-1-yanfei.xu@bytedance.com I can observe more than 10% reduction of average page fault latency during postcopy phase with this optimization: Before: 268.00us (+-1.87%) After: 232.67us (+-2.01%) The test was done with a 16GB VM with 80 vCPUs, running a workload that busy random writes to 13GB memory. Cc: Yanfei Xu Reviewed-by: Fabiano Rosas Signed-off-by: Peter Xu --- migration/ram.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/migration/ram.c b/migration/ram.c index a1d0e8ada2..cd4aafd15c 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -835,8 +835,10 @@ static inline bool migration_bitmap_clear_dirty(RAMSta= te *rs, * protections isn't needed as we know there will be either (1) no * further writes if migration will complete, or (2) migration fails * at last then tracking isn't needed either. + * + * Do the same for postcopy due to the same reason. */ - if (!rs->last_stage) { + if (!rs->last_stage && !migration_in_postcopy()) { /* * Clear dirty bitmap if needed. This _must_ be called before we * send any of the page in the chunk because we need to make sure --=20 2.49.0