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dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:45390 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kVFGL-00081N-G0 for qemu-devel@archiver.kernel.org; Wed, 21 Oct 2020 10:38:49 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53034) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kVFEy-0007GL-I0 for qemu-devel@nongnu.org; Wed, 21 Oct 2020 10:37:24 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:33706) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kVFEv-0005Kw-5B for qemu-devel@nongnu.org; Wed, 21 Oct 2020 10:37:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603291040; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=xSONFPb+ZIC16rLcLPqN4MRZ1u1CM7Sn+vrQzX68dR8=; b=fpxQgB21CNTYxY/5jxjCgGTSoch+Z4Tz0XZpdzpNcAvEDC2Vdu2Ul+jwvET7mrgvi/frkn W2lsAUEuKj+3aPks94zg/tDQ6c3JPJ80yCwrn2Wzu17De2c+Z6HvF4206UQ+f8N3Inp4HN mnwioC9+nxWG+fMiU81sBKni3ELbtWs= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-453-ryawNlF9O2GGTMm0VpPAgw-1; Wed, 21 Oct 2020 10:37:18 -0400 X-MC-Unique: ryawNlF9O2GGTMm0VpPAgw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 904DB1074666; Wed, 21 Oct 2020 14:37:17 +0000 (UTC) Received: from work-vm (ovpn-114-232.ams2.redhat.com [10.36.114.232]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5F61B5D9DD; Wed, 21 Oct 2020 14:37:10 +0000 (UTC) Date: Wed, 21 Oct 2020 15:37:07 +0100 From: "Dr. David Alan Gilbert" To: Peter Xu Subject: Re: [PATCH v5 4/6] migration: Sync requested pages after postcopy recovery Message-ID: <20201021143707.GE3671@work-vm> References: <20201019225720.172743-1-peterx@redhat.com> <20201019225720.172743-5-peterx@redhat.com> MIME-Version: 1.0 In-Reply-To: <20201019225720.172743-5-peterx@redhat.com> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/21 02:16:02 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] 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_H4=0.001, RCVD_IN_MSPIKE_WL=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Thomas Huth , Xiaohui Li , qemu-devel@nongnu.org, Juan Quintela Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Peter Xu (peterx@redhat.com) wrote: > We synchronize the requested pages right after a postcopy recovery happens. > This helps to synchronize the prioritized pages on source so that the faulted > threads can be served faster. > > Reported-by: Xiaohui Li > Signed-off-by: Peter Xu Reviewed-by: Dr. David Alan Gilbert > --- > migration/savevm.c | 57 ++++++++++++++++++++++++++++++++++++++++++ > migration/trace-events | 1 + > 2 files changed, 58 insertions(+) > > diff --git a/migration/savevm.c b/migration/savevm.c > index d2e141f7b1..33acbba1a4 100644 > --- a/migration/savevm.c > +++ b/migration/savevm.c > @@ -2011,6 +2011,49 @@ static int loadvm_postcopy_handle_run(MigrationIncomingState *mis) > return LOADVM_QUIT; > } > > +/* We must be with page_request_mutex held */ > +static gboolean postcopy_sync_page_req(gpointer key, gpointer value, > + gpointer data) > +{ > + MigrationIncomingState *mis = data; > + void *host_addr = (void *) key; > + ram_addr_t rb_offset; > + RAMBlock *rb; > + int ret; > + > + rb = qemu_ram_block_from_host(host_addr, true, &rb_offset); > + if (!rb) { > + /* > + * This should _never_ happen. However be nice for a migrating VM to > + * not crash/assert. Post an error (note: intended to not use *_once > + * because we do want to see all the illegal addresses; and this can > + * never be triggered by the guest so we're safe) and move on next. > + */ > + error_report("%s: illegal host addr %p", __func__, host_addr); > + /* Try the next entry */ > + return FALSE; > + } > + > + ret = migrate_send_rp_message_req_pages(mis, rb, rb_offset); > + if (ret) { > + /* Please refer to above comment. */ > + error_report("%s: send rp message failed for addr %p", > + __func__, host_addr); > + return FALSE; > + } > + > + trace_postcopy_page_req_sync(host_addr); > + > + return FALSE; > +} > + > +static void migrate_send_rp_req_pages_pending(MigrationIncomingState *mis) > +{ > + WITH_QEMU_LOCK_GUARD(&mis->page_request_mutex) { > + g_tree_foreach(mis->page_requested, postcopy_sync_page_req, mis); > + } > +} > + > static int loadvm_postcopy_handle_resume(MigrationIncomingState *mis) > { > if (mis->state != MIGRATION_STATUS_POSTCOPY_RECOVER) { > @@ -2033,6 +2076,20 @@ static int loadvm_postcopy_handle_resume(MigrationIncomingState *mis) > /* Tell source that "we are ready" */ > migrate_send_rp_resume_ack(mis, MIGRATION_RESUME_ACK_VALUE); > > + /* > + * After a postcopy recovery, the source should have lost the postcopy > + * queue, or potentially the requested pages could have been lost during > + * the network down phase. Let's re-sync with the source VM by re-sending > + * all the pending pages that we eagerly need, so these threads won't get > + * blocked too long due to the recovery. > + * > + * Without this procedure, the faulted destination VM threads (waiting for > + * page requests right before the postcopy is interrupted) can keep hanging > + * until the pages are sent by the source during the background copying of > + * pages, or another thread faulted on the same address accidentally. > + */ > + migrate_send_rp_req_pages_pending(mis); > + > return 0; > } > > diff --git a/migration/trace-events b/migration/trace-events > index e4d5eb94ca..0fbfd2da60 100644 > --- a/migration/trace-events > +++ b/migration/trace-events > @@ -49,6 +49,7 @@ vmstate_save(const char *idstr, const char *vmsd_name) "%s, %s" > vmstate_load(const char *idstr, const char *vmsd_name) "%s, %s" > postcopy_pause_incoming(void) "" > postcopy_pause_incoming_continued(void) "" > +postcopy_page_req_sync(void *host_addr) "sync page req %p" > > # vmstate.c > vmstate_load_field_error(const char *field, int ret) "field \"%s\" load failed, ret = %d" > -- > 2.26.2 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK