From nobody Mon Feb 9 23:02:11 2026 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=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1669039035; cv=none; d=zohomail.com; s=zohoarc; b=l4WketDMDbFOo96ToozMmL1o1HJyVG4m3j3WIh9eLiAwxCiZ+IuHhDl2nBg1UDkd254nEVQD4bLAlfxxkmAi3PrI+56m+LzRezAyFODdNHEoleGsIsEw3umkmBmpQXXYeGouHrwHOb/1Rxe1WFxlFq/5VU8Yxvo77v2cUQf/UNw= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1669039035; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=30+Kq9dPR7peGz5envehc+sa5UbYD15LI+w9Psis5To=; b=oL9RARgDN4lLqW+30EquczRhqtbNXkQqZVHpEE2G+N++6gX8ru6MCoetTaw6aDSFXzDRw0lqM0blOeoIUMgrhVVcYM0it0F3tXx4Nf+bYI2eZXJGrwYTfjweqnO2ckvagK+vw6l1GZuVeA+KK98SJU3/XguKLMvGw00AnPqAYBY= 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=none dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1669039035171909.6007954368757; Mon, 21 Nov 2022 05:57:15 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ox6rq-0001KS-6o; Mon, 21 Nov 2022 08:29:46 -0500 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 1ox6rP-0000oj-4Q for qemu-devel@nongnu.org; Mon, 21 Nov 2022 08:29:19 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ox6qZ-0004t0-R5 for qemu-devel@nongnu.org; Mon, 21 Nov 2022 08:29:18 -0500 Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-225-vKpOes1nOiaHxTFnrI2G3Q-1; Mon, 21 Nov 2022 08:27:55 -0500 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 999A8811E81; Mon, 21 Nov 2022 13:27:54 +0000 (UTC) Received: from secure.mitica (unknown [10.39.193.227]) by smtp.corp.redhat.com (Postfix) with ESMTP id D98064B3FC6; Mon, 21 Nov 2022 13:27:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669037279; 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=30+Kq9dPR7peGz5envehc+sa5UbYD15LI+w9Psis5To=; b=BUpJCatNLV/JWoqO3kHGfGpPPg8bqpU2I9e9JgWQXI7VzsnGnM2tauc5SViVFlMPzFqsmo aJ5UOeQAVmQfiHjesZ+7nCogtr2cAVpPVSiLgerm6H4kXJ0dOEmhGKYwxPsE2aOpwBejfx OCNCDn8/g6zOlWdZE95MdPrIvyRL+U8= X-MC-Unique: vKpOes1nOiaHxTFnrI2G3Q-1 From: Juan Quintela To: qemu-devel@nongnu.org Cc: Juan Quintela , "Dr. David Alan Gilbert" , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , Thomas Huth , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , Paolo Bonzini , Fam Zheng , Peter Xu , Michael Tokarev , Stefan Hajnoczi , qemu-block@nongnu.org, =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , David Hildenbrand , qemu-trivial@nongnu.org, Laurent Vivier Subject: [PATCH 10/19] migration: Yield bitmap_mutex properly when sending/sleeping Date: Mon, 21 Nov 2022 14:27:08 +0100 Message-Id: <20221121132717.63070-11-quintela@redhat.com> In-Reply-To: <20221121132717.63070-1-quintela@redhat.com> References: <20221121132717.63070-1-quintela@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 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=170.10.129.124; envelope-from=quintela@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: 1669039036156100001 Content-Type: text/plain; charset="utf-8" From: Peter Xu Don't take the bitmap mutex when sending pages, or when being throttled by migration_rate_limit() (which is a bit tricky to call it here in ram code, but seems still helpful). It prepares for the possibility of concurrently sending pages in >1 threads using the function ram_save_host_page() because all threads may need the bitmap_mutex to operate on bitmaps, so that either sendmsg() or any kind of qemu_sem_wait() blocking for one thread will not block the other from progressing. Signed-off-by: Peter Xu Reviewed-by: Juan Quintela Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Juan Quintela --- migration/ram.c | 46 +++++++++++++++++++++++++++++++++++----------- 1 file changed, 35 insertions(+), 11 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index 6e3dc845c5..5379164749 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -2452,9 +2452,14 @@ static void postcopy_preempt_reset_channel(RAMState = *rs) * a host page in which case the remainder of the hostpage is sent. * Only dirty target pages are sent. Note that the host page size may * be a huge page for this block. + * * The saving stops at the boundary of the used_length of the block * if the RAMBlock isn't a multiple of the host page size. * + * The caller must be with ram_state.bitmap_mutex held to call this + * function. Note that this function can temporarily release the lock, but + * when the function is returned it'll make sure the lock is still held. + * * Returns the number of pages written or negative on error * * @rs: current RAM state @@ -2462,6 +2467,7 @@ static void postcopy_preempt_reset_channel(RAMState *= rs) */ static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss) { + bool page_dirty, preempt_active =3D postcopy_preempt_active(); int tmppages, pages =3D 0; size_t pagesize_bits =3D qemu_ram_pagesize(pss->block) >> TARGET_PAGE_BITS; @@ -2485,22 +2491,40 @@ static int ram_save_host_page(RAMState *rs, PageSea= rchStatus *pss) break; } =20 + page_dirty =3D migration_bitmap_clear_dirty(rs, pss->block, pss->p= age); + /* Check the pages is dirty and if it is send it */ - if (migration_bitmap_clear_dirty(rs, pss->block, pss->page)) { + if (page_dirty) { + /* + * Properly yield the lock only in postcopy preempt mode + * because both migration thread and rp-return thread can + * operate on the bitmaps. + */ + if (preempt_active) { + qemu_mutex_unlock(&rs->bitmap_mutex); + } tmppages =3D ram_save_target_page(rs, pss); - if (tmppages < 0) { - return tmppages; + if (tmppages >=3D 0) { + pages +=3D tmppages; + /* + * Allow rate limiting to happen in the middle of huge pag= es if + * something is sent in the current iteration. + */ + if (pagesize_bits > 1 && tmppages > 0) { + migration_rate_limit(); + } } - - pages +=3D tmppages; - /* - * Allow rate limiting to happen in the middle of huge pages if - * something is sent in the current iteration. - */ - if (pagesize_bits > 1 && tmppages > 0) { - migration_rate_limit(); + if (preempt_active) { + qemu_mutex_lock(&rs->bitmap_mutex); } + } else { + tmppages =3D 0; + } + + if (tmppages < 0) { + return tmppages; } + pss->page =3D migration_bitmap_find_dirty(rs, pss->block, pss->pag= e); } while ((pss->page < hostpage_boundary) && offset_in_ramblock(pss->block, --=20 2.38.1