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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 70B70C47089 for ; Mon, 5 Dec 2022 10:04:49 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1p28ES-00059P-Fc; Mon, 05 Dec 2022 04:57:52 -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 1p28EH-00051h-D8 for qemu-devel@nongnu.org; Mon, 05 Dec 2022 04:57:43 -0500 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 1p28EE-0007wn-GL for qemu-devel@nongnu.org; Mon, 05 Dec 2022 04:57:40 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1670234256; 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=YX/4/NL1H166JhAOhrTvC62e1FuNY3SDJAcJ9A74Gunq1qRwaLTlQp3W+dEDctpAouENjJ HLENIRFVeBcXG/JvFyO5OT3PgZFTCXx5WzJjHpK5j8Tf7wlm5Nmz8A4BXo25AS1gHNVXV/ wm4ABlCihV8kvsjzy62lDOVu4QwKVxo= 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-510-31Nfrau3OC2NYJZxgScheA-1; Mon, 05 Dec 2022 04:57:31 -0500 X-MC-Unique: 31Nfrau3OC2NYJZxgScheA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id EBF4A87B2A1; Mon, 5 Dec 2022 09:57:29 +0000 (UTC) Received: from secure.mitica (unknown [10.39.194.135]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6700A2166B29; Mon, 5 Dec 2022 09:57:22 +0000 (UTC) From: Juan Quintela To: qemu-devel@nongnu.org Cc: Fam Zheng , Thomas Huth , Viresh Kumar , Kevin Wolf , Mathieu Poirier , Laurent Vivier , Eric Blake , Richard Henderson , Raphael Norwitz , Stefan Hajnoczi , Juan Quintela , virtio-fs@redhat.com, =?UTF-8?q?Alex=20Benn=C3=A9e?= , Christian Borntraeger , "Gonglei (Arei)" , qemu-block@nongnu.org, Xiaojuan Yang , Thomas Huth , Ilya Leoshkevich , Eduardo Habkost , Gerd Hoffmann , "Dr. David Alan Gilbert" , Alex Williamson , Eric Farman , Halil Pasic , Peter Maydell , Vladimir Sementsov-Ogievskiy , Jason Wang , Laurent Vivier , Song Gao , qemu-s390x@nongnu.org, Pavel Dovgalyuk , Klaus Jensen , John Snow , Michael Tokarev , qemu-arm@nongnu.org, Paolo Bonzini , "Michael S. Tsirkin" , Keith Busch , David Hildenbrand , qemu-trivial@nongnu.org, Hanna Reitz , Peter Xu Subject: [PATCH v2 37/51] migration: Yield bitmap_mutex properly when sending/sleeping Date: Mon, 5 Dec 2022 10:52:14 +0100 Message-Id: <20221205095228.1314-38-quintela@redhat.com> In-Reply-To: <20221205095228.1314-1-quintela@redhat.com> References: <20221205095228.1314-1-quintela@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 Received-SPF: pass client-ip=170.10.133.124; envelope-from=quintela@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_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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org 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 = postcopy_preempt_active(); int tmppages, pages = 0; size_t pagesize_bits = qemu_ram_pagesize(pss->block) >> TARGET_PAGE_BITS; @@ -2485,22 +2491,40 @@ static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss) break; } + page_dirty = migration_bitmap_clear_dirty(rs, pss->block, pss->page); + /* 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 = ram_save_target_page(rs, pss); - if (tmppages < 0) { - return tmppages; + if (tmppages >= 0) { + pages += 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(); + } } - - pages += 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 = 0; + } + + if (tmppages < 0) { + return tmppages; } + pss->page = migration_bitmap_find_dirty(rs, pss->block, pss->page); } while ((pss->page < hostpage_boundary) && offset_in_ramblock(pss->block, -- 2.38.1