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, USER_AGENT_SANE_1 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 77250C33CA9 for ; Mon, 13 Jan 2020 02:23:26 +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 4BBB821556 for ; Mon, 13 Jan 2020 02:23:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4BBB821556 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:44742 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iqpO1-0006nz-H2 for qemu-devel@archiver.kernel.org; Sun, 12 Jan 2020 21:23:25 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:39186) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iqpNP-0006Fw-Be for qemu-devel@nongnu.org; Sun, 12 Jan 2020 21:22:48 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iqpNN-0001LF-TS for qemu-devel@nongnu.org; Sun, 12 Jan 2020 21:22:47 -0500 Received: from mga17.intel.com ([192.55.52.151]:6741) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iqpNN-0001E9-L1 for qemu-devel@nongnu.org; Sun, 12 Jan 2020 21:22:45 -0500 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Jan 2020 18:22:39 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,427,1571727600"; d="scan'208";a="272913293" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by FMSMGA003.fm.intel.com with ESMTP; 12 Jan 2020 18:22:38 -0800 Date: Mon, 13 Jan 2020 10:22:31 +0800 From: Wei Yang To: Wei Yang Subject: Re: [PATCH] migration/postcopy: not necessary to discard all RAM at the beginning Message-ID: <20200113022231.GA14173@richard> References: <20191007091008.9435-1-richardw.yang@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191007091008.9435-1-richardw.yang@linux.intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 192.55.52.151 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: , Reply-To: Wei Yang Cc: qemu-devel@nongnu.org, dgilbert@redhat.com, quintela@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Oops, this one seems to be missed. On Mon, Oct 07, 2019 at 05:10:08PM +0800, Wei Yang wrote: >ram_discard_range() unmap page for specific range. To be specific, this >clears related page table entries so that userfault would be triggered. >But this step is not necessary at the very beginning. > >ram_postcopy_incoming_init() is called when destination gets ADVISE >command. ADVISE command is sent when migration thread just starts, which >implies destination is not running yet. This means no page fault >happened and memory region's page tables entries are empty. > >This patch removes the discard at the beginning. > >Signed-off-by: Wei Yang >--- > migration/postcopy-ram.c | 46 ---------------------------------------- > migration/postcopy-ram.h | 7 ------ > migration/ram.c | 16 -------------- > migration/ram.h | 1 - > migration/savevm.c | 4 ---- > 5 files changed, 74 deletions(-) > >diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c >index 5da6de8c8b..459be8e780 100644 >--- a/migration/postcopy-ram.c >+++ b/migration/postcopy-ram.c >@@ -443,32 +443,6 @@ out: > return ret; > } > >-/* >- * Setup an area of RAM so that it *can* be used for postcopy later; this >- * must be done right at the start prior to pre-copy. >- * opaque should be the MIS. >- */ >-static int init_range(RAMBlock *rb, void *opaque) >-{ >- const char *block_name = qemu_ram_get_idstr(rb); >- void *host_addr = qemu_ram_get_host_addr(rb); >- ram_addr_t offset = qemu_ram_get_offset(rb); >- ram_addr_t length = qemu_ram_get_used_length(rb); >- trace_postcopy_init_range(block_name, host_addr, offset, length); >- >- /* >- * We need the whole of RAM to be truly empty for postcopy, so things >- * like ROMs and any data tables built during init must be zero'd >- * - we're going to get the copy from the source anyway. >- * (Precopy will just overwrite this data, so doesn't need the discard) >- */ >- if (ram_discard_range(block_name, 0, length)) { >- return -1; >- } >- >- return 0; >-} >- > /* > * At the end of migration, undo the effects of init_range > * opaque should be the MIS. >@@ -506,20 +480,6 @@ static int cleanup_range(RAMBlock *rb, void *opaque) > return 0; > } > >-/* >- * Initialise postcopy-ram, setting the RAM to a state where we can go into >- * postcopy later; must be called prior to any precopy. >- * called from arch_init's similarly named ram_postcopy_incoming_init >- */ >-int postcopy_ram_incoming_init(MigrationIncomingState *mis) >-{ >- if (foreach_not_ignored_block(init_range, NULL)) { >- return -1; >- } >- >- return 0; >-} >- > /* > * Manage a single vote to the QEMU balloon inhibitor for all postcopy usage, > * last caller wins. >@@ -1282,12 +1242,6 @@ bool postcopy_ram_supported_by_host(MigrationIncomingState *mis) > return false; > } > >-int postcopy_ram_incoming_init(MigrationIncomingState *mis) >-{ >- error_report("postcopy_ram_incoming_init: No OS support"); >- return -1; >-} >- > int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis) > { > assert(0); >diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h >index c0ccf64a96..1c79c6e51f 100644 >--- a/migration/postcopy-ram.h >+++ b/migration/postcopy-ram.h >@@ -22,13 +22,6 @@ bool postcopy_ram_supported_by_host(MigrationIncomingState *mis); > */ > int postcopy_ram_incoming_setup(MigrationIncomingState *mis); > >-/* >- * Initialise postcopy-ram, setting the RAM to a state where we can go into >- * postcopy later; must be called prior to any precopy. >- * called from ram.c's similarly named ram_postcopy_incoming_init >- */ >-int postcopy_ram_incoming_init(MigrationIncomingState *mis); >- > /* > * At the end of a migration where postcopy_ram_incoming_init was called. > */ >diff --git a/migration/ram.c b/migration/ram.c >index dfc50d57d5..9a853703d8 100644 >--- a/migration/ram.c >+++ b/migration/ram.c >@@ -4015,22 +4015,6 @@ static int ram_load_cleanup(void *opaque) > return 0; > } > >-/** >- * ram_postcopy_incoming_init: allocate postcopy data structures >- * >- * Returns 0 for success and negative if there was one error >- * >- * @mis: current migration incoming state >- * >- * Allocate data structures etc needed by incoming migration with >- * postcopy-ram. postcopy-ram's similarly names >- * postcopy_ram_incoming_init does the work. >- */ >-int ram_postcopy_incoming_init(MigrationIncomingState *mis) >-{ >- return postcopy_ram_incoming_init(mis); >-} >- > /** > * ram_load_postcopy: load a page in postcopy case > * >diff --git a/migration/ram.h b/migration/ram.h >index 44fe4753ad..66cbff1d52 100644 >--- a/migration/ram.h >+++ b/migration/ram.h >@@ -58,7 +58,6 @@ void ram_postcopy_migrated_memory_release(MigrationState *ms); > int ram_postcopy_send_discard_bitmap(MigrationState *ms); > /* For incoming postcopy discard */ > int ram_discard_range(const char *block_name, uint64_t start, size_t length); >-int ram_postcopy_incoming_init(MigrationIncomingState *mis); > bool postcopy_is_running(void); > > void ram_handle_compressed(void *host, uint8_t ch, uint64_t size); >diff --git a/migration/savevm.c b/migration/savevm.c >index 9dc191e0a0..d2a427a3bf 100644 >--- a/migration/savevm.c >+++ b/migration/savevm.c >@@ -1674,10 +1674,6 @@ static int loadvm_postcopy_handle_advise(MigrationIncomingState *mis, > return -1; > } > >- if (ram_postcopy_incoming_init(mis)) { >- return -1; >- } >- > return 0; > } > >-- >2.17.1 -- Wei Yang Help you, Help me