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(Postfix) id CC3CE608BA; Mon, 21 Jun 2021 14:05:15 +0000 (UTC) Received: from T590 (ovpn-12-104.pek2.redhat.com [10.72.12.104]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 38A2C60853; Mon, 21 Jun 2021 14:04:59 +0000 (UTC) Date: Mon, 21 Jun 2021 22:04:54 +0800 From: Ming Lei To: JeffleXu Message-ID: References: <20210617103549.930311-1-ming.lei@redhat.com> <20210617103549.930311-4-ming.lei@redhat.com> <5ba43dac-b960-7c85-3a89-fdae2d1e2f51@linux.alibaba.com> <9b42601a-ca54-4748-e592-3720b7994d7b@linux.alibaba.com> MIME-Version: 1.0 In-Reply-To: <9b42601a-ca54-4748-e592-3720b7994d7b@linux.alibaba.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-loop: dm-devel@redhat.com Cc: Jens Axboe , linux-block@vger.kernel.org, dm-devel@redhat.com, Christoph Hellwig , Mike Snitzer Subject: Re: [dm-devel] [RFC PATCH V2 3/3] dm: support bio polling X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: 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(majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229890AbhFUOHe (ORCPT ); Mon, 21 Jun 2021 10:07:34 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:44794 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229747AbhFUOHe (ORCPT ); Mon, 21 Jun 2021 10:07:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624284319; 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=upfGk/98pZA3QPB7oLwR+MhWulCYYbB02mWSMUEUjto=; b=SDa/94fMh5TetvADTMwzke2gr63Nwv6kbtftSamNoBLjKywE8wT1EKK6Vh5jWrcXob6DwT XNpK2Pas5AnuQbFlfjjNFVwtHMFWAVpVH024R6qefKwKD0neTEg58qZ/F2BXn8n/iVzHst BpI7FM06iTLiaRQxrnVj7IysOBao2pg= 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-529-F8WHfA80MJ2mAUFgVXYtQQ-1; Mon, 21 Jun 2021 10:05:18 -0400 X-MC-Unique: F8WHfA80MJ2mAUFgVXYtQQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CED461054F98; Mon, 21 Jun 2021 14:05:15 +0000 (UTC) Received: from T590 (ovpn-12-104.pek2.redhat.com [10.72.12.104]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 38A2C60853; Mon, 21 Jun 2021 14:04:59 +0000 (UTC) Date: Mon, 21 Jun 2021 22:04:54 +0800 From: Ming Lei To: JeffleXu Cc: Jens Axboe , Mike Snitzer , linux-block@vger.kernel.org, dm-devel@redhat.com, Christoph Hellwig Subject: Re: [dm-devel] [RFC PATCH V2 3/3] dm: support bio polling Message-ID: References: <20210617103549.930311-1-ming.lei@redhat.com> <20210617103549.930311-4-ming.lei@redhat.com> <5ba43dac-b960-7c85-3a89-fdae2d1e2f51@linux.alibaba.com> <9b42601a-ca54-4748-e592-3720b7994d7b@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9b42601a-ca54-4748-e592-3720b7994d7b@linux.alibaba.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Mon, Jun 21, 2021 at 07:33:34PM +0800, JeffleXu wrote: > > > On 6/18/21 10:39 PM, Ming Lei wrote: > > From 47e523b9ee988317369eaadb96826323cd86819e Mon Sep 17 00:00:00 2001 > > From: Ming Lei > > Date: Wed, 16 Jun 2021 16:13:46 +0800 > > Subject: [RFC PATCH V3 3/3] dm: support bio polling > > > > Support bio(REQ_POLLED) polling in the following approach: > > > > 1) only support io polling on normal READ/WRITE, and other abnormal IOs > > still fallback on IRQ mode, so the target io is exactly inside the dm > > io. > > > > 2) hold one refcnt on io->io_count after submitting this dm bio with > > REQ_POLLED > > > > 3) support dm native bio splitting, any dm io instance associated with > > current bio will be added into one list which head is bio->bi_end_io > > which will be recovered before ending this bio > > > > 4) implement .poll_bio() callback, call bio_poll() on the single target > > bio inside the dm io which is retrieved via bio->bi_bio_drv_data; call > > dec_pending() after the target io is done in .poll_bio() > > > > 4) enable QUEUE_FLAG_POLL if all underlying queues enable QUEUE_FLAG_POLL, > > which is based on Jeffle's previous patch. > > > > Signed-off-by: Ming Lei > > --- > > V3: > > - covers all comments from Jeffle > > - fix corner cases when polling on abnormal ios > > > ... > > One bug and one performance issue, though I haven't investigated deep > for both. > > > kernel base: based on Jens' for-next, applying Christoph and Leiming's > patchset. > > > 1. One bug when there's DM device stack, e.g., dm-linear upon another > dm-linear. Can be reproduced by following steps: > > ``` > $ sudo dmsetup create tmpdev --table '0 2097152 linear /dev/nvme0n1 0' > > $ cat tmp.table > 0 2097152 linear /dev/mapper/tmpdev 0 > 2097152 2097152 linear /dev/nvme0n1 0 > > $ cat tmp.table | dmsetup create testdev > > $ fio -name=test -ioengine=io_uring -iodepth=128 -numjobs=1 -thread > -rw=randread -direct=1 -bs=4k -time_based -runtime=10 -cpus_allowed=6 > -filename=/dev/mapper/testdev -hipri=1 > ``` > > > BUG: unable to handle page fault for address: ffffffffc01a6208 > #PF: supervisor write access in kernel mode > #PF: error_code(0x0003) - permissions violation > PGD 39740c067 P4D 39740c067 PUD 39740e067 PMD 1035db067 PTE 1ddf6f061 > Oops: 0003 [#1] SMP PTI > CPU: 6 PID: 5899 Comm: fio Tainted: G S > 5.13.0-0.1.git.81bcdc3.al7.x86_64 #1 > Hardware name: Inventec K900G3-10G/B900G3, BIOS A2.20 06/23/2017 > RIP: 0010:dm_submit_bio+0x171/0x3e0 [dm_mod] It has been fixed in my local repo: @@ -1608,6 +1649,7 @@ static void init_clone_info(struct clone_info *ci, struct mapped_device *md, ci->map = map; ci->io = alloc_io(md, bio); ci->sector = bio->bi_iter.bi_sector; + ci->submit_as_polled = false; > > > 2. Performance Issue > > I test both on x86 (with only one NVMe) and aarch64 (with multiple NVMes). > > The result (IOPS) on x86 is as expected: > > Type |IRQ | Polling > --------- | ---- | ---- > dm-linear | 239k | 357k > > - dm-linear built upon one NVMe，bs=4k, iopoll=1, iodepth=128, > numjobs=1, direct, randread, ioengine=io_uring This data looks good. > > > > While the result on aarch64 is a little confusing. > > Type |IRQ | Polling > ------------- | ---- | ---- > dm-linear [1] | 208k | 230k > dm-linear [2] | 637k | 691k > dm-stripe | 310k | 354k > > - dm-linear [1] built upon *one* NVMe，bs=4k, iopoll=1, iodepth=128, > *numjobs=1*, direct, randread, ioengine=io_uring > - dm-linear [2] built upon *three* NVMes，bs=4k, iopoll=1, iodepth=128, > *numjobs=3*, direct, randread, ioengine=io_uring > - dm-stripe built upon *three* NVMes，chunk_size=4k, bs=12k, iopoll=1, > iodepth=128, numjobs=3, direct, randread, ioengine=io_uring > > > Following is the corresponding test result of Leiming's last > implementation for bio-based polling on aarch64. > IRQ IOPOLL ratio > dm-linear [2] 639K 835K ~30% > dm-stripe 314K 408K ~30% The previous version polls one hw queue once if bios are submitted to same hw queue. We might improve it in future. Thanks, Ming