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, URIBL_BLOCKED,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 15183C31E40 for ; Wed, 7 Aug 2019 00:16:21 +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 E0833216F4 for ; Wed, 7 Aug 2019 00:16:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E0833216F4 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]:36752 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hv9cq-0003AR-3q for qemu-devel@archiver.kernel.org; Tue, 06 Aug 2019 20:16:20 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34604) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hv9cF-0002gW-FP for qemu-devel@nongnu.org; Tue, 06 Aug 2019 20:15:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hv9cE-0001K3-92 for qemu-devel@nongnu.org; Tue, 06 Aug 2019 20:15:43 -0400 Received: from mga02.intel.com ([134.134.136.20]:53553) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hv9cE-0001JG-0T for qemu-devel@nongnu.org; Tue, 06 Aug 2019 20:15:42 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Aug 2019 17:15:09 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,353,1559545200"; d="scan'208";a="174333029" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by fmsmga008.fm.intel.com with ESMTP; 06 Aug 2019 17:15:07 -0700 Date: Wed, 7 Aug 2019 08:14:45 +0800 From: Wei Yang To: "Dr. David Alan Gilbert" Message-ID: <20190807001445.GA24750@richard> References: <20190806004648.8659-1-richardw.yang@linux.intel.com> <20190806004648.8659-2-richardw.yang@linux.intel.com> <20190806145117.GF3066@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190806145117.GF3066@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: 134.134.136.20 Subject: Re: [Qemu-devel] [PATCH 1/2] migration/postcopy: simplify calculation of run_start and fixup_start_addr 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: 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, Aug 06, 2019 at 03:51:17PM +0100, Dr. David Alan Gilbert wrote: >* Wei Yang (richardw.yang@linux.intel.com) wrote: >> The purpose of the calculation is to find a HostPage which is partially >> dirty. >> >> * fixup_start_addr points to the start of the HostPage to discard >> * run_start points to the next HostPage to check >> >> While in the middle stage, there would two cases for run_start: >> >> * aligned with HostPage means this is not partially dirty >> * not aligned means this is partially dirty >> >> When it is aligned, no work and calculation is necessary. run_start >> already points to the start of next HostPage and is ready to continue. >> >> When it is not aligned, the calculation could be simplified with: >> >> * fixup_start_addr = QEMU_ALIGN_DOWN(run_start, host_ratio) >> * run_start = QEMU_ALIGN_UP(run_start, host_ratio) >> >> By doing so, run_start always points to the next HostPage to check. >> fixup_start_addr always points to the HostPage to discard. >> >> Signed-off-by: Wei Yang > >Yes that's a lot shorter; note it doess it on top of your cleanup >from a couple of weeks back. > You are right, I forget to mention it :-) >Reviewed-by: Dr. David Alan Gilbert > > >> --- >> migration/ram.c | 34 +++++++--------------------------- >> 1 file changed, 7 insertions(+), 27 deletions(-) >> >> diff --git a/migration/ram.c b/migration/ram.c >> index c9585487ac..d86661a015 100644 >> --- a/migration/ram.c >> +++ b/migration/ram.c >> @@ -2956,7 +2956,6 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass, >> } >> >> while (run_start < pages) { >> - unsigned long fixup_start_addr; >> unsigned long host_offset; >> >> /* >> @@ -2964,45 +2963,26 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass, >> * page, then we need to fixup this host page. >> */ >> host_offset = run_start % host_ratio; >> - if (host_offset) { >> - fixup_start_addr = run_start - host_offset; >> - /* >> - * This host page has gone, the next loop iteration starts >> - * from after the fixup >> - */ >> - run_start = fixup_start_addr + host_ratio; >> - } else { >> + if (!host_offset) { >> /* Find the end of this run */ >> - unsigned long run_end; >> if (unsent_pass) { >> - run_end = find_next_bit(unsentmap, pages, run_start + 1); >> + run_start = find_next_bit(unsentmap, pages, run_start + 1); >> } else { >> - run_end = find_next_zero_bit(bitmap, pages, run_start + 1); >> + run_start = find_next_zero_bit(bitmap, pages, run_start + 1); >> } >> /* >> * If the end isn't at the start of a host page, then the >> * run doesn't finish at the end of a host page >> * and we need to discard. >> */ >> - host_offset = run_end % host_ratio; >> - if (host_offset) { >> - fixup_start_addr = run_end - host_offset; >> - /* >> - * This host page has gone, the next loop iteration starts >> - * from after the fixup >> - */ >> - run_start = fixup_start_addr + host_ratio; >> - } else { >> - /* >> - * No discards on this iteration, next loop starts from >> - * next sent/dirty page >> - */ >> - run_start = run_end + 1; >> - } >> + host_offset = run_start % host_ratio; >> } >> >> if (host_offset) { >> unsigned long page; >> + unsigned long fixup_start_addr = QEMU_ALIGN_DOWN(run_start, >> + 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)) { >> -- >> 2.17.1 >> >-- >Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK -- Wei Yang Help you, Help me