From nobody Sun Feb 8 18:30:01 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=intel.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1544519025116837.1935994909315; Tue, 11 Dec 2018 01:03:45 -0800 (PST) Received: from localhost ([::1]:36643 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gWdx3-00067j-Jh for importer@patchew.org; Tue, 11 Dec 2018 04:03:37 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51638) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gWdrk-0002Yk-Fd for qemu-devel@nongnu.org; Tue, 11 Dec 2018 03:58:09 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gWdrh-0006LJ-I1 for qemu-devel@nongnu.org; Tue, 11 Dec 2018 03:58:08 -0500 Received: from mga07.intel.com ([134.134.136.100]:27021) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gWdrh-0006FH-87 for qemu-devel@nongnu.org; Tue, 11 Dec 2018 03:58:05 -0500 Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Dec 2018 00:58:04 -0800 Received: from devel-ww.sh.intel.com ([10.239.48.119]) by orsmga001.jf.intel.com with ESMTP; 11 Dec 2018 00:58:02 -0800 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,341,1539673200"; d="scan'208";a="117803156" From: Wei Wang To: qemu-devel@nongnu.org, virtio-dev@lists.oasis-open.org, mst@redhat.com, quintela@redhat.com, dgilbert@redhat.com, peterx@redhat.com Date: Tue, 11 Dec 2018 16:24:52 +0800 Message-Id: <1544516693-5395-7-git-send-email-wei.w.wang@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1544516693-5395-1-git-send-email-wei.w.wang@intel.com> References: <1544516693-5395-1-git-send-email-wei.w.wang@intel.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 134.134.136.100 Subject: [Qemu-devel] [PATCH v11 6/7] migration/ram.c: add the free page optimization enable flag 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: pbonzini@redhat.com, liliang.opensource@gmail.com, nilal@redhat.com, wei.w.wang@intel.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" This patch adds the free page optimization enable flag, and a function to set this flag. When the free page optimization is enabled, not all the pages are needed to be sent in the bulk stage. Why using a new flag, instead of directly disabling ram_bulk_stage when the optimization is running? Thanks for Peter Xu's reminder that disabling ram_bulk_stage will affect the use of compression. Please see save_page_use_compression. When xbzrle and compression are used, if free page optimizaion causes the ram_bulk_stage to be disabled, save_page_use_compression will return false, which disables the use of compression. That is, if free page optimization avoids the sending of half of the guest pages, the other half of pages loses the benefits of compression in the meantime. Using a new flag to let migration_bitmap_find_dirty skip the free pages in the bulk stage will avoid the above issue. Signed-off-by: Wei Wang CC: Dr. David Alan Gilbert CC: Juan Quintela CC: Michael S. Tsirkin CC: Peter Xu --- include/migration/misc.h | 1 + migration/ram.c | 18 +++++++++++++++++- 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/include/migration/misc.h b/include/migration/misc.h index 15f8d00..1227279 100644 --- a/include/migration/misc.h +++ b/include/migration/misc.h @@ -37,6 +37,7 @@ void precopy_infrastructure_init(void); void precopy_add_notifier(NotifierWithReturn *n); void precopy_remove_notifier(NotifierWithReturn *n); int precopy_notify(PrecopyNotifyReason reason, Error **errp); +void precopy_enable_free_page_optimization(void); =20 void ram_mig_init(void); void qemu_guest_free_page_hint(void *addr, size_t len); diff --git a/migration/ram.c b/migration/ram.c index 1e00d92..188bbad 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -290,6 +290,8 @@ struct RAMState { uint32_t last_version; /* We are in the first round */ bool ram_bulk_stage; + /* The free page optimization is enabled */ + bool fpo_enabled; /* How many times we have dirty too many pages */ int dirty_rate_high_cnt; /* these variables are used for bitmap sync */ @@ -354,6 +356,15 @@ int precopy_notify(PrecopyNotifyReason reason, Error *= *errp) return notifier_with_return_list_notify(&precopy_notifier_list, &pnd); } =20 +void precopy_enable_free_page_optimization(void) +{ + if (!ram_state) { + return; + } + + ram_state->fpo_enabled =3D true; +} + uint64_t ram_bytes_remaining(void) { return ram_state ? (ram_state->migration_dirty_pages * TARGET_PAGE_SIZ= E) : @@ -1567,7 +1578,11 @@ unsigned long migration_bitmap_find_dirty(RAMState *= rs, RAMBlock *rb, return size; } =20 - if (rs->ram_bulk_stage && start > 0) { + /* + * When the free page optimization is enabled, we need to check the bi= tmap + * to send the non-free pages rather than all the pages in the bulk st= age. + */ + if (!rs->fpo_enabled && rs->ram_bulk_stage && start > 0) { next =3D start + 1; } else { next =3D find_next_bit(bitmap, size, start); @@ -2600,6 +2615,7 @@ static void ram_state_reset(RAMState *rs) rs->last_page =3D 0; rs->last_version =3D ram_list.version; rs->ram_bulk_stage =3D true; + rs->fpo_enabled =3D false; } =20 #define MAX_WAIT 50 /* ms, half buffered_file limit */ --=20 1.8.3.1