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 B495CC432C1 for ; Wed, 25 Sep 2019 00:27:21 +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 7AACA20872 for ; Wed, 25 Sep 2019 00:27:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7AACA20872 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]:44354 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iCv9M-0007rh-Do for qemu-devel@archiver.kernel.org; Tue, 24 Sep 2019 20:27:20 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58747) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iCv8K-0007FI-Nn for qemu-devel@nongnu.org; Tue, 24 Sep 2019 20:26:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iCv8J-00049V-HQ for qemu-devel@nongnu.org; Tue, 24 Sep 2019 20:26:16 -0400 Received: from mga11.intel.com ([192.55.52.93]:10643) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iCv8J-000485-8R for qemu-devel@nongnu.org; Tue, 24 Sep 2019 20:26:15 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Sep 2019 17:26:08 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,545,1559545200"; d="scan'208";a="340245699" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by orsmga004.jf.intel.com with ESMTP; 24 Sep 2019 17:26:06 -0700 Date: Wed, 25 Sep 2019 08:25:47 +0800 From: Wei Yang To: "Dr. David Alan Gilbert" Subject: Re: [PATCH 1/3] migration/postcopy: not necessary to do discard when canonicalizing bitmap Message-ID: <20190925002547.GA19466@richard> References: <20190819061843.28642-1-richardw.yang@linux.intel.com> <20190819061843.28642-2-richardw.yang@linux.intel.com> <20190924100208.GA2725@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190924100208.GA2725@work-vm> 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: 192.55.52.93 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: pbonzini@redhat.com, quintela@redhat.com, Wei Yang , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Sep 24, 2019 at 11:02:08AM +0100, Dr. David Alan Gilbert wrote: >* Wei Yang (richardw.yang@linux.intel.com) wrote: >> All pages, either partially sent or partially dirty, will be discarded in >> postcopy_send_discard_bm_ram(), since we update the unsentmap to be >> unsentmap = unsentmap | dirty in ram_postcopy_send_discard_bitmap(). >> >> This is not necessary to do discard when canonicalizing bitmap. And by >> doing so, we separate the page discard into two individual steps: >> >> * canonicalize bitmap >> * discard page >> >> Signed-off-by: Wei Yang > >Yes, I think when I originally wrote it, the set of pages that was >discarded was different; I think it was actually the set of >!unsent & dirty - i.e. only pages that had been sent and then redirtied; >it later got reworked to include unsent pages as well - so this lot can >be simplified. > > Thanks for your time :-) > >Reviewed-by: Dr. David Alan Gilbert > >> --- >> migration/ram.c | 14 +------------- >> 1 file changed, 1 insertion(+), 13 deletions(-) >> >> diff --git a/migration/ram.c b/migration/ram.c >> index 35552c090b..075ddc468c 100644 >> --- a/migration/ram.c >> +++ b/migration/ram.c >> @@ -2928,7 +2928,7 @@ static int postcopy_each_ram_send_discard(MigrationState *ms) >> } >> >> /** >> - * postcopy_chunk_hostpages_pass: canocalize bitmap in hostpages >> + * postcopy_chunk_hostpages_pass: canonicalize bitmap in hostpages >> * >> * Helper for postcopy_chunk_hostpages; it's called twice to >> * canonicalize the two bitmaps, that are similar, but one is >> @@ -2991,18 +2991,6 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass, >> host_ratio); >> run_start = QEMU_ALIGN_UP(run_start, host_ratio); >> >> - /* Tell the destination to discard this page */ >> - if (unsent_pass || !test_bit(fixup_start_addr, unsentmap)) { >> - /* For the unsent_pass we: >> - * discard partially sent pages >> - * For the !unsent_pass (dirty) we: >> - * discard partially dirty pages that were sent >> - * (any partially sent pages were already discarded >> - * by the previous unsent_pass) >> - */ >> - postcopy_discard_send_range(ms, fixup_start_addr, host_ratio); >> - } >> - >> /* Clean up the bitmap */ >> for (page = fixup_start_addr; >> page < fixup_start_addr + host_ratio; page++) { >> -- >> 2.17.1 >> >-- >Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK -- Wei Yang Help you, Help me