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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, T_HK_NAME_DR,USER_AGENT_MUTT 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 E0C65C282DD for ; Mon, 10 Jun 2019 10:59:57 +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 B8EFA2082E for ; Mon, 10 Jun 2019 10:59:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B8EFA2082E Authentication-Results: mail.kernel.org; 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]:44304 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1haI1t-0003FO-2Z for qemu-devel@archiver.kernel.org; Mon, 10 Jun 2019 06:59:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:37682) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1haHy7-0000hy-Lc for qemu-devel@nongnu.org; Mon, 10 Jun 2019 06:56:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1haHy6-00036k-1j for qemu-devel@nongnu.org; Mon, 10 Jun 2019 06:56:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54300) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1haHy5-00031G-2Z for qemu-devel@nongnu.org; Mon, 10 Jun 2019 06:56:01 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3894D13AAE; Mon, 10 Jun 2019 10:55:59 +0000 (UTC) Received: from work-vm (ovpn-117-16.ams2.redhat.com [10.36.117.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5B8AA5C207; Mon, 10 Jun 2019 10:55:58 +0000 (UTC) Date: Mon, 10 Jun 2019 11:55:55 +0100 From: "Dr. David Alan Gilbert" To: Wei Yang Message-ID: <20190610105555.GD22439@work-vm> References: <20190610004159.20966-1-richardw.yang@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190610004159.20966-1-richardw.yang@linux.intel.com> User-Agent: Mutt/1.11.4 (2019-03-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Mon, 10 Jun 2019 10:55:59 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v2] migration/xbzrle: update cache and current_data in one place 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, quintela@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Wei Yang (richardw.yang@linux.intel.com) wrote: > When we are not in the last_stage, we need to update the cache if page > is not the same. > > Currently this procedure is scattered in two places and mixed with > encoding status check. > > This patch extract this general step out to make the code a little bit > easy to read. > > Signed-off-by: Wei Yang > Reviewed-by: Dr. David Alan Gilbert > --- > v2: give more comment on the behavior > --- > migration/ram.c | 25 +++++++++++++++---------- > 1 file changed, 15 insertions(+), 10 deletions(-) > > diff --git a/migration/ram.c b/migration/ram.c > index e9b40d636d..17cc9b2b44 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -1594,25 +1594,30 @@ static int save_xbzrle_page(RAMState *rs, uint8_t **current_data, > encoded_len = xbzrle_encode_buffer(prev_cached_page, XBZRLE.current_buf, > TARGET_PAGE_SIZE, XBZRLE.encoded_buf, > TARGET_PAGE_SIZE); > + > + /* > + * Update the cache contents, so that it corresponds to the data > + * sent, in all cases except where we skip the page. > + */ > + if (!last_stage && encoded_len != 0) { > + memcpy(prev_cached_page, XBZRLE.current_buf, TARGET_PAGE_SIZE); > + /* > + * In the case where we couldn't compress, ensure that the caller > + * sends the data from the cache, since the guest might have > + * changed the RAM since we copied it. > + */ > + *current_data = prev_cached_page; > + } > + > if (encoded_len == 0) { > trace_save_xbzrle_page_skipping(); > return 0; > } else if (encoded_len == -1) { > trace_save_xbzrle_page_overflow(); > xbzrle_counters.overflow++; > - /* update data in the cache */ > - if (!last_stage) { > - memcpy(prev_cached_page, *current_data, TARGET_PAGE_SIZE); > - *current_data = prev_cached_page; > - } > return -1; > } > > - /* we need to update the data in the cache, in order to get the same data */ > - if (!last_stage) { > - memcpy(prev_cached_page, XBZRLE.current_buf, TARGET_PAGE_SIZE); > - } > - > /* Send XBZRLE based compressed page */ > bytes_xbzrle = save_page_header(rs, rs->f, block, > offset | RAM_SAVE_FLAG_XBZRLE); > -- > 2.19.1 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK