From patchwork Mon Jun 10 10:14:20 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Lieven X-Patchwork-Id: 250207 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 769C52C030F for ; Mon, 10 Jun 2013 20:16:41 +1000 (EST) Received: from localhost ([::1]:35140 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ulz9T-0006iT-FV for incoming@patchwork.ozlabs.org; Mon, 10 Jun 2013 06:16:39 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43027) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ulz8x-0006dh-Bu for qemu-devel@nongnu.org; Mon, 10 Jun 2013 06:16:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ulz8s-0001ip-En for qemu-devel@nongnu.org; Mon, 10 Jun 2013 06:16:07 -0400 Received: from mx.ipv6.kamp.de ([2a02:248:0:51::16]:45222 helo=mx01.kamp.de) by eggs.gnu.org with smtp (Exim 4.71) (envelope-from ) id 1Ulz8s-0001id-4N for qemu-devel@nongnu.org; Mon, 10 Jun 2013 06:16:02 -0400 Received: (qmail 22121 invoked by uid 89); 10 Jun 2013 10:16:01 -0000 Received: from [82.141.1.145] by client-16-kamp (envelope-from , uid 89) with qmail-scanner-2.01 (clamdscan: 0.97.8/17328. hbedv: 8.2.12.30/7.11.74.24. spamassassin: 3.3.1. Clear:RC:1(82.141.1.145):SA:0(-1.6/5.0):. Processed in 9.65438 secs); 10 Jun 2013 10:16:01 -0000 Received: from ns.kamp-intra.net (HELO dns.kamp-intra.net) ([82.141.1.145]) by mx01.kamp.de with SMTP; 10 Jun 2013 10:15:51 -0000 X-GL_Whitelist: yes Received: from lieven-pc.kamp-intra.net (lieven-pc.kamp-intra.net [172.21.12.60]) by dns.kamp-intra.net (Postfix) with ESMTP id 7D4F6206A6; Mon, 10 Jun 2013 12:14:31 +0200 (CEST) Received: by lieven-pc.kamp-intra.net (Postfix, from userid 1000) id BB63A5FD19; Mon, 10 Jun 2013 12:14:31 +0200 (CEST) From: Peter Lieven To: qemu-devel@nongnu.org Date: Mon, 10 Jun 2013 12:14:20 +0200 Message-Id: <1370859260-8183-3-git-send-email-pl@kamp.de> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1370859260-8183-1-git-send-email-pl@kamp.de> References: <1370859260-8183-1-git-send-email-pl@kamp.de> X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2a02:248:0:51::16 Cc: quintela@redhat.com, aik@ozlabs.ru, Peter Lieven , owasserm@redhat.com, pbonzini@redhat.com, xiawenc@linux.vnet.ibm.com, david@gibson.dropbear.id.au Subject: [Qemu-devel] [PATCHv2 2/2] migration: do not overwrite zero pages X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org on incoming migration do not memset pages to zero if they already read as zero. this will allocate a new zero page and consume memory unnecessarily. even if we madvise a MADV_DONTNEED later this will only deallocate the memory asynchronously. Signed-off-by: Peter Lieven Reviewed-by: Michael Roth Reviewed-by: Orit Wasserman --- arch_init.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/arch_init.c b/arch_init.c index 08fccf6..cf4e1d5 100644 --- a/arch_init.c +++ b/arch_init.c @@ -832,14 +832,16 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) } ch = qemu_get_byte(f); - memset(host, ch, TARGET_PAGE_SIZE); + if (ch != 0 || !is_zero_page(host)) { + memset(host, ch, TARGET_PAGE_SIZE); #ifndef _WIN32 - if (ch == 0 && - (!kvm_enabled() || kvm_has_sync_mmu()) && - getpagesize() <= TARGET_PAGE_SIZE) { - qemu_madvise(host, TARGET_PAGE_SIZE, QEMU_MADV_DONTNEED); - } + if (ch == 0 && + (!kvm_enabled() || kvm_has_sync_mmu()) && + getpagesize() <= TARGET_PAGE_SIZE) { + qemu_madvise(host, TARGET_PAGE_SIZE, QEMU_MADV_DONTNEED); + } #endif + } } else if (flags & RAM_SAVE_FLAG_PAGE) { void *host;