From patchwork Fri May 19 21:59:02 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Felipe Franciosi X-Patchwork-Id: 9738281 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 92B346034C for ; Fri, 19 May 2017 22:00:13 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8438D28585 for ; Fri, 19 May 2017 22:00:13 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 770CD28588; Fri, 19 May 2017 22:00:13 +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 0437A28585 for ; Fri, 19 May 2017 22:00:12 +0000 (UTC) Received: from localhost ([::1]:60391 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dBpwS-0002Ty-4s for patchwork-qemu-devel@patchwork.kernel.org; Fri, 19 May 2017 18:00:12 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58002) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dBpvp-0002Tt-9U for qemu-devel@nongnu.org; Fri, 19 May 2017 17:59:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dBpvm-0003Zi-81 for qemu-devel@nongnu.org; Fri, 19 May 2017 17:59:33 -0400 Received: from [62.254.189.133] (port=52428 helo=centos.localdomain) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dBpvl-0003P2-Sz for qemu-devel@nongnu.org; Fri, 19 May 2017 17:59:30 -0400 Received: by centos.localdomain (Postfix, from userid 500) id 6DB8D9FD42; Fri, 19 May 2017 22:59:04 +0100 (BST) From: Felipe Franciosi To: Juan Quintela , "Jason J. Herne" Date: Fri, 19 May 2017 22:59:02 +0100 Message-Id: <1495231142-19055-1-git-send-email-felipe@nutanix.com> X-Mailer: git-send-email 1.9.5 X-detected-operating-system: by eggs.gnu.org: Mac OS X [generic] [fuzzy] X-Received-From: 62.254.189.133 Subject: [Qemu-devel] [PATCH] 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: "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 ~ --- migration/ram.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index f59fdd4..793af39 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -670,10 +670,6 @@ 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); }