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 X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 96236CA9EA0 for ; Sat, 26 Oct 2019 00:48:03 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 5F46F21872 for ; Sat, 26 Oct 2019 00:48:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5F46F21872 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:37626 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iOAFO-0004xc-5l for qemu-devel@archiver.kernel.org; Fri, 25 Oct 2019 20:48:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54975) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iOADB-0002aS-SJ for qemu-devel@nongnu.org; Fri, 25 Oct 2019 20:45:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iOADA-0004kv-Ra for qemu-devel@nongnu.org; Fri, 25 Oct 2019 20:45:45 -0400 Received: from mga01.intel.com ([192.55.52.88]:5552) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iOADA-0004k9-Jt for qemu-devel@nongnu.org; Fri, 25 Oct 2019 20:45:44 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Oct 2019 17:45:44 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,230,1569308400"; d="scan'208";a="204705109" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by FMSMGA003.fm.intel.com with ESMTP; 25 Oct 2019 17:45:43 -0700 From: Wei Yang To: quintela@redhat.com, dgilbert@redhat.com Subject: [PATCH v2 2/6] migration/multifd: notify channels_ready when send thread starts Date: Sat, 26 Oct 2019 08:45:16 +0800 Message-Id: <20191026004520.5515-3-richardw.yang@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191026004520.5515-1-richardw.yang@linux.intel.com> References: <20191026004520.5515-1-richardw.yang@linux.intel.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 192.55.52.88 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: qemu-devel@nongnu.org, Wei Yang Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" multifd_send_state->channels_ready is initialized to 0. It is proper to let main thread know we are ready when thread start running. Current implementation works since ram_save_setup() calls multifd_send_sync_main() which wake up send thread and posts channels_ready. This behavior will introduce some unpredictable situation and disturb the semaphore value. This is a preparation patch to use another mechanism to do send thread synchronization to avoid post channels_ready in this case. So this patch posts channels_ready when send threads start running. Signed-off-by: Wei Yang --- migration/ram.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/migration/ram.c b/migration/ram.c index 35f147388b..25d477796e 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1107,6 +1107,8 @@ static void *multifd_send_thread(void *opaque) } /* initial packet */ p->num_packets = 1; + /* let main thread know we are ready */ + qemu_sem_post(&multifd_send_state->channels_ready); while (true) { qemu_sem_wait(&p->sem); -- 2.17.1