From patchwork Wed May 24 16:10:00 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Felipe Franciosi X-Patchwork-Id: 9746357 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 755EC6032B for ; Wed, 24 May 2017 16:12:04 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 655C728985 for ; Wed, 24 May 2017 16:12:04 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 59BC1289B6; Wed, 24 May 2017 16:12:04 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 8FE57289B4 for ; Wed, 24 May 2017 16:12:02 +0000 (UTC) Received: from localhost ([::1]:55830 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dDYtF-0004Pn-P9 for patchwork-qemu-devel@patchwork.kernel.org; Wed, 24 May 2017 12:12:01 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54836) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dDYs1-0004Ni-BS for qemu-devel@nongnu.org; Wed, 24 May 2017 12:10:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dDYrx-0001ki-AU for qemu-devel@nongnu.org; Wed, 24 May 2017 12:10:45 -0400 Received: from [62.254.189.133] (port=10573 helo=centos.localdomain) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dDYrw-0001e2-Uz for qemu-devel@nongnu.org; Wed, 24 May 2017 12:10:41 -0400 Received: by centos.localdomain (Postfix, from userid 500) id 1815A9FCD3; Wed, 24 May 2017 17:10:16 +0100 (BST) From: Felipe Franciosi To: Peter Xu , Juan Quintela , "Jason J. Herne" , amit Shah , "Dr. David Alan Gilbert" Date: Wed, 24 May 2017 17:10:00 +0100 Message-Id: <1495642203-12702-2-git-send-email-felipe@nutanix.com> X-Mailer: git-send-email 1.9.5 In-Reply-To: <1495642203-12702-1-git-send-email-felipe@nutanix.com> References: <1495642203-12702-1-git-send-email-felipe@nutanix.com> X-detected-operating-system: by eggs.gnu.org: Mac OS X [generic] [fuzzy] X-Received-From: 62.254.189.133 Subject: [Qemu-devel] [PATCH 1/4] migration: keep bytes_xfer_prev init'd to zero X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Malcolm Crossley , "qemu-devel@nongnu.org" , Felipe Franciosi Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP The first time migration_bitmap_sync() is called, bytes_xfer_prev is set to ram_state.bytes_transferred which is, at this point, zero. The next time migration_bitmap_sync() is called, an iteration has happened and bytes_xfer_prev is set to 'x' bytes. Most likely, more than one second has passed, so the auto converge logic will be triggered and bytes_xfer_now will also be set to 'x' bytes. This condition is currently masked by dirty_rate_high_cnt, which will wait for a few iterations before throttling. It would otherwise always assume zero bytes have been copied and therefore throttle the guest (possibly) prematurely. Given bytes_xfer_prev is only used by the auto convergence logic, it makes sense to only set its value after a check has been made against bytes_xfer_now. Signed-off-by: Felipe Franciosi Reviewed-by: Peter Xu Reviewed-by: Juan Quintela --- migration/ram.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index c07a9c0..36bf720 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -673,10 +673,6 @@ static void migration_bitmap_sync(RAMState *rs) rs->bitmap_sync_count++; - if (!rs->bytes_xfer_prev) { - rs->bytes_xfer_prev = ram_bytes_transferred(); - } - if (!rs->time_last_bitmap_sync) { rs->time_last_bitmap_sync = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); }