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=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 D30BFC433DB for ; Fri, 5 Mar 2021 17:47:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A9520650A1 for ; Fri, 5 Mar 2021 17:47:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229631AbhCERqh (ORCPT ); Fri, 5 Mar 2021 12:46:37 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:44968 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230047AbhCERqe (ORCPT ); Fri, 5 Mar 2021 12:46:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1614966393; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2mNrC0Eq4RRwqxhwpA3GPSQmWFWAXRl4b39T5Sq16P4=; b=VTOCeBi4/8YQ1CxOfogt1eJejXumpUknIKFasVF16etnnpzlo1vq1IHhVHuYqavyLb6zrC TUO/L36jlq06RszknmcapPlSAXz12qx7uhVu8IOSml2xqdBsUvCPcZZ7zWzgoJl4ayVU2Y qZi7Oxz+6aPJrwe7zLtwqgIEt75F6MI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-397-qRldupvZN2aG-LMF1Fax0g-1; Fri, 05 Mar 2021 12:46:29 -0500 X-MC-Unique: qRldupvZN2aG-LMF1Fax0g-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E81538015A1; Fri, 5 Mar 2021 17:46:27 +0000 (UTC) Received: from [192.168.1.10] (ovpn-114-106.ams2.redhat.com [10.36.114.106]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8A1A05D6B1; Fri, 5 Mar 2021 17:46:25 +0000 (UTC) Subject: Re: [dm-devel] [PATCH 4/4] dm: support I/O polling To: JeffleXu , Mikulas Patocka Cc: axboe@kernel.dk, Mike Snitzer , caspar@linux.alibaba.com, hch@lst.de, linux-block@vger.kernel.org, joseph.qi@linux.alibaba.com, dm-devel@redhat.com, io-uring@vger.kernel.org References: <20210302190555.201228400@debian-a64.vm> <33fa121a-88a8-5c27-0a43-a7efc9b5b3e3@linux.alibaba.com> <157a750d-3d58-ae2e-07f1-b677c1b471c7@linux.alibaba.com> From: Heinz Mauelshagen Message-ID: Date: Fri, 5 Mar 2021 18:46:24 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <157a750d-3d58-ae2e-07f1-b677c1b471c7@linux.alibaba.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 3/5/21 10:52 AM, JeffleXu wrote: > > On 3/3/21 6:09 PM, Mikulas Patocka wrote: >> >> On Wed, 3 Mar 2021, JeffleXu wrote: >> >>> >>> On 3/3/21 3:05 AM, Mikulas Patocka wrote: >>> >>>> Support I/O polling if submit_bio_noacct_mq_direct returned non-empty >>>> cookie. >>>> >>>> Signed-off-by: Mikulas Patocka >>>> >>>> --- >>>> drivers/md/dm.c | 5 +++++ >>>> 1 file changed, 5 insertions(+) >>>> >>>> Index: linux-2.6/drivers/md/dm.c >>>> =================================================================== >>>> --- linux-2.6.orig/drivers/md/dm.c 2021-03-02 19:26:34.000000000 +0100 >>>> +++ linux-2.6/drivers/md/dm.c 2021-03-02 19:26:34.000000000 +0100 >>>> @@ -1682,6 +1682,11 @@ static void __split_and_process_bio(stru >>>> } >>>> } >>>> >>>> + if (ci.poll_cookie != BLK_QC_T_NONE) { >>>> + while (atomic_read(&ci.io->io_count) > 1 && >>>> + blk_poll(ci.poll_queue, ci.poll_cookie, true)) ; >>>> + } >>>> + >>>> /* drop the extra reference count */ >>>> dec_pending(ci.io, errno_to_blk_status(error)); >>>> } >>> It seems that the general idea of your design is to >>> 1) submit *one* split bio >>> 2) blk_poll(), waiting the previously submitted split bio complets >> No, I submit all the bios and poll for the last one. >> >>> and then submit next split bio, repeating the above process. I'm afraid >>> the performance may be an issue here, since the batch every time >>> blk_poll() reaps may decrease. >> Could you benchmark it? > I only tested dm-linear. > > The configuration (dm table) of dm-linear is: > 0 1048576 linear /dev/nvme0n1 0 > 1048576 1048576 linear /dev/nvme2n1 0 > 2097152 1048576 linear /dev/nvme5n1 0 > > > fio script used is: > ``` > $cat fio.conf > [global] > name=iouring-sqpoll-iopoll-1 > ioengine=io_uring > iodepth=128 > numjobs=1 > thread > rw=randread > direct=1 > registerfiles=1 > hipri=1 > runtime=10 > time_based > group_reporting > randrepeat=0 > filename=/dev/mapper/testdev > bs=4k > > [job-1] > cpus_allowed=14 > ``` > > IOPS (IRQ mode) | IOPS (iopoll mode (hipri=1)) > --------------- | -------------------- > 213k | 19k > > At least, it doesn't work well with io_uring interface. > > Jeffe, I ran your above fio test on a linear LV split across 3 NVMes to second your split mapping (system: 32 core Intel, 256GiB RAM) comparing io engines sync, libaio and io_uring, the latter w/ and w/o hipri (sync+libaio obviously w/o registerfiles and hipri) which resulted ok: sync  |  libaio  |  IRQ mode (hipri=0) | iopoll (hipri=1) ------|----------|---------------------|----------------- 56.3K |    290K  |                329K |             351K I can't second your drastic hipri=1 drop here... Heinz