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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 4A2F8C433DB for ; Mon, 1 Mar 2021 07:35:05 +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 7011B64DE5 for ; Mon, 1 Mar 2021 07:35:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7011B64DE5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:37028 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lGd55-0006E8-4y for qemu-devel@archiver.kernel.org; Mon, 01 Mar 2021 02:35:03 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:60796) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lGd3x-0005mc-7Y for qemu-devel@nongnu.org; Mon, 01 Mar 2021 02:33:53 -0500 Received: from szxga03-in.huawei.com ([45.249.212.189]:2193) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lGd3u-00020g-52 for qemu-devel@nongnu.org; Mon, 01 Mar 2021 02:33:52 -0500 Received: from DGGEMM405-HUB.china.huawei.com (unknown [172.30.72.54]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4DpsQB5qJdz56d8; Mon, 1 Mar 2021 15:31:30 +0800 (CST) Received: from dggema765-chm.china.huawei.com (10.1.198.207) by DGGEMM405-HUB.china.huawei.com (10.3.20.213) with Microsoft SMTP Server (TLS) id 14.3.498.0; Mon, 1 Mar 2021 15:33:36 +0800 Received: from [10.174.185.210] (10.174.185.210) by dggema765-chm.china.huawei.com (10.1.198.207) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2106.2; Mon, 1 Mar 2021 15:33:36 +0800 Subject: Re: [PATCH 3/3] migration/ram: Optimize ram_save_host_page() To: David Edmondson , Juan Quintela , "Dr . David Alan Gilbert" , "open list:All patches CC here" References: <20210223021646.500-1-jiangkunkun@huawei.com> <20210223021646.500-4-jiangkunkun@huawei.com> From: Kunkun Jiang Message-ID: <5438e9c9-2eee-5a2b-8a30-24c0d707e125@huawei.com> Date: Mon, 1 Mar 2021 15:33:22 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.174.185.210] X-ClientProxiedBy: dggeme706-chm.china.huawei.com (10.1.199.102) To dggema765-chm.china.huawei.com (10.1.198.207) X-CFilter-Loop: Reflected Received-SPF: pass client-ip=45.249.212.189; envelope-from=jiangkunkun@huawei.com; helo=szxga03-in.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: , Cc: Zenghui Yu , wanghaibin.wang@huawei.com, Keqian Zhu Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2021/2/25 20:48, David Edmondson wrote: > On Tuesday, 2021-02-23 at 10:16:45 +08, Kunkun Jiang wrote: > >> Starting from pss->page, ram_save_host_page() will check every page >> and send the dirty pages up to the end of the current host page or >> the boundary of used_length of the block. If the host page size is >> a huge page, the step "check" will take a lot of time. >> >> This will improve performance to use migration_bitmap_find_dirty(). >> >> Signed-off-by: Keqian Zhu >> Signed-off-by: Kunkun Jiang >> --- >> migration/ram.c | 14 ++++++++------ >> 1 file changed, 8 insertions(+), 6 deletions(-) >> >> diff --git a/migration/ram.c b/migration/ram.c >> index c7e18dc2fc..c7a2350198 100644 >> --- a/migration/ram.c >> +++ b/migration/ram.c >> @@ -1994,6 +1994,8 @@ static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss, >> int tmppages, pages = 0; >> size_t pagesize_bits = >> qemu_ram_pagesize(pss->block) >> TARGET_PAGE_BITS; >> + unsigned long hostpage_boundary = >> + QEMU_ALIGN_UP(pss->page + 1, pagesize_bits); >> unsigned long start_page = pss->page; >> int res; >> >> @@ -2005,8 +2007,7 @@ static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss, >> do { >> /* Check the pages is dirty and if it is send it */ >> if (!migration_bitmap_clear_dirty(rs, pss->block, pss->page)) { >> - pss->page++; >> - continue; >> + goto find_next; >> } >> >> tmppages = ram_save_target_page(rs, pss, last_stage); >> @@ -2015,16 +2016,17 @@ static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss, >> } >> >> pages += tmppages; >> - pss->page++; >> /* Allow rate limiting to happen in the middle of huge pages */ >> if (pagesize_bits > 1) { >> migration_rate_limit(); >> } >> - } while ((pss->page & (pagesize_bits - 1)) && >> +find_next: >> + pss->page = migration_bitmap_find_dirty(rs, pss->block, pss->page); >> + } while ((pss->page < hostpage_boundary) && >> offset_in_ramblock(pss->block, >> ((ram_addr_t)pss->page) << TARGET_PAGE_BITS)); > This ends up looking very messy, with a goto inside the loop. > > Wouldn't it be cleaner to invert the sense of the > migration_bitmap_clear_dirty() test, such that > migration_bitmap_find_dirty() is called after the body of the test? Sorry for the late reply. Thanks for your advice.  I will post a v2 as soon as possible. Best Regards. Kunkun Jiang >> - /* The offset we leave with is the last one we looked at */ >> - pss->page--; >> + /* The offset we leave with is the min boundary of host page and block */ >> + pss->page = MIN(pss->page, hostpage_boundary) - 1; >> >> res = ram_save_release_protection(rs, pss, start_page); >> return (res < 0 ? res : pages); >> -- >> 2.23.0 > dme.