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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8172FC6FD1D for ; Fri, 17 Mar 2023 08:16:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229770AbjCQIQw (ORCPT ); Fri, 17 Mar 2023 04:16:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44928 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229806AbjCQIQs (ORCPT ); Fri, 17 Mar 2023 04:16:48 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8DDA0CB078 for ; Fri, 17 Mar 2023 01:15:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1679040858; 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: in-reply-to:in-reply-to:references:references; bh=1cmIrOKszNs0jnWEfQ0Vr7pU28RoEwOK9ywsBoDJefQ=; b=gez9qO5ILsYz0q25wU0ycgfJj2SVNcDIPp7fX5+1cvd4TaQnrogFljv+rOKox4pkl+KShI b7/bIkMfKVLhBz3XUPYW2nw6AwvS+2/V+3tihLWuRcJidkgv+Z8YrUddq1qVxf3ZCLp+Qy z1YwofmZ92EQKUzoXnWt3YXdtZWZIMc= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-510-EI68wD6hPFONH5Zuc1nEyg-1; Fri, 17 Mar 2023 04:14:15 -0400 X-MC-Unique: EI68wD6hPFONH5Zuc1nEyg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8D6C9299E760; Fri, 17 Mar 2023 08:14:14 +0000 (UTC) Received: from ovpn-8-18.pek2.redhat.com (ovpn-8-18.pek2.redhat.com [10.72.8.18]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 838C62027047; Fri, 17 Mar 2023 08:14:09 +0000 (UTC) Date: Fri, 17 Mar 2023 16:14:03 +0800 From: Ming Lei To: Jens Axboe , io-uring@vger.kernel.org, linux-block@vger.kernel.org Cc: Miklos Szeredi , ZiyangZhang , Xiaoguang Wang , Bernd Schubert , Pavel Begunkov , ming.lei@redhat.com Subject: Re: [PATCH V3 00/16] io_uring/ublk: add IORING_OP_FUSED_CMD Message-ID: References: <20230314125727.1731233-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230314125727.1731233-1-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Tue, Mar 14, 2023 at 08:57:11PM +0800, Ming Lei wrote: > Hello, > > Add IORING_OP_FUSED_CMD, it is one special URING_CMD, which has to > be SQE128. The 1st SQE(master) is one 64byte URING_CMD, and the 2nd > 64byte SQE(slave) is another normal 64byte OP. For any OP which needs > to support slave OP, io_issue_defs[op].fused_slave needs to be set as 1, > and its ->issue() can retrieve/import buffer from master request's > fused_cmd_kbuf. The slave OP is actually submitted from kernel, part of > this idea is from Xiaoguang's ublk ebpf patchset, but this patchset > submits slave OP just like normal OP issued from userspace, that said, > SQE order is kept, and batching handling is done too. > > Please see detailed design in commit log of the 2th patch, and one big > point is how to handle buffer ownership. > > With this way, it is easy to support zero copy for ublk/fuse device. > > Basically userspace can specify any sub-buffer of the ublk block request > buffer from the fused command just by setting 'offset/len' > in the slave SQE for running slave OP. This way is flexible to implement > io mapping: mirror, stripped, ... > > The 3th & 4th patches enable fused slave support for the following OPs: > > OP_READ/OP_WRITE > OP_SEND/OP_RECV/OP_SEND_ZC > > The other ublk patches cleans ublk driver and implement fused command > for supporting zero copy. > > Follows userspace code: > > https://github.com/ming1/ubdsrv/tree/fused-cmd-zc-v2 > > All three(loop, nbd and qcow2) ublk targets have supported zero copy by passing: > > ublk add -t [loop|nbd|qcow2] -z .... > > Basic fs mount/kernel building and builtin test are done, and also not > observe regression on xfstest test over ublk-loop with zero copy. > > Also add liburing test case for covering fused command based on miniublk > of blktest: > > https://github.com/ming1/liburing/commits/fused_cmd_miniublk > > Performance improvement is obvious on memory bandwidth > related workloads, such as, 1~2X improvement on 64K/512K BS > IO test on loop with ramfs backing file. > > Any comments are welcome! > > V3: > - fix build warning reported by kernel test robot > - drop patch for checking fused flags on existed drivers with > ->uring_command(), which isn't necessary, since we do not do that > when adding new ioctl or uring command > - inline io_init_rq() for core code, so just export io_init_slave_req > - return result of failed slave request unconditionally since REQ_F_CQE_SKIP > will be cleared > - pass xfstest over ublk-loop Hello Jens and Guys, I have been working on io_uring zero copy support for ublk/fuse for a while, and I appreciate you may share any thoughts on this patchset or approach? Thanks, Ming