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=DKIM_SIGNED,DKIM_VALID, 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 C6AFEC433E0 for ; Fri, 19 Jun 2020 15:56:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9DAA020809 for ; Fri, 19 Jun 2020 15:56:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="Q8BM5Kms" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392728AbgFSPUk (ORCPT ); Fri, 19 Jun 2020 11:20:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58758 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392719AbgFSPUh (ORCPT ); Fri, 19 Jun 2020 11:20:37 -0400 Received: from mail-pl1-x642.google.com (mail-pl1-x642.google.com [IPv6:2607:f8b0:4864:20::642]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 637BEC0613EF for ; Fri, 19 Jun 2020 08:20:35 -0700 (PDT) Received: by mail-pl1-x642.google.com with SMTP id k1so4050717pls.2 for ; Fri, 19 Jun 2020 08:20:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=5wyT4zhpVGaiWZ+0VMPzFsJ8IbyK09OnFrAoYFHELAA=; b=Q8BM5Kmsr4PGo3gqetyGVs7kF64+h7ZpjdoJouL5y7jX+q/iIm0oDGsz4ojT6o9w0M UJpR9D6q5VY9Mq/g6MAQVf+N+QH9gZLJ6fX4zjbjYaGBHzloyTVJLvBHapV9QNDDGzB1 3lkRtzBMRvuvHH7ZmhP3QLOp1j2biNhLlu7sl7/+nY4ZuMZmCIyiQL2XGFc0FhEyQWSM lKidnoe9ysLsLbptvwqfnbOnxRuHw3k3fNikTK1gTqeXRMzxXcodal/jBFL7MZIdlOWA kQf1BGqxw3SDZbXcb4TsRZyLRuV/TcHYYRWoRSsnnjOUBvpSqHKv5Yorx+5daAcKbS21 Xuyw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=5wyT4zhpVGaiWZ+0VMPzFsJ8IbyK09OnFrAoYFHELAA=; b=rkqvYVF8npyYA7UhCJWKs8He9xkqo+DFSrly24J6DSWMjV/QwYSJL+7ffh7IYt/ktZ valsf+LZVuY8Y0Cl7yK5FgJ0P8UhP/0vUTDTCB55le9LSAOarWUA3169UWAI7VTO/ZcP IE9BFoWLiL/YK/21v3eI1mu6r25bccchKMNEXzTc91MhY01Urn0JyorWuWI0krdsGfiK fkKiS/VoQS9/a1NWdpL8I8GnN9byG51dd5ZIlKMSDjv3UX3rvkhA00J6PAEc0ATJHR0D WiUWt84DqAaBLtg+B7ofpPOCwHJtp6whiU+4JhZ0ttshPkZGL5t1PjtfvGqs6Z813WSg b1dw== X-Gm-Message-State: AOAM5302hmLI3+Yr0aAxoYpdtBwnHv3vN7guYXBxVYk0H00FkEtCLIR6 vUOD3INXi6/6PkQ4gkrDZn+RJw== X-Google-Smtp-Source: ABdhPJyI6dZ6veIhT+4ahN1VGBYPXSiufUd6I/qBRzkiUcVGW/zHHYm1yb+WfYHs+rLLR8lPs7W9kg== X-Received: by 2002:a17:902:9b8e:: with SMTP id y14mr8582774plp.109.1592580035070; Fri, 19 Jun 2020 08:20:35 -0700 (PDT) Received: from [192.168.1.188] ([66.219.217.173]) by smtp.gmail.com with ESMTPSA id t201sm6238118pfc.104.2020.06.19.08.20.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 19 Jun 2020 08:20:34 -0700 (PDT) Subject: Re: [PATCH 3/3] io_uring: add support for zone-append To: =?UTF-8?Q?Matias_Bj=c3=b8rling?= , "javier.gonz@samsung.com" , Damien Le Moal Cc: Kanchan Joshi , "viro@zeniv.linux.org.uk" , "bcrl@kvack.org" , "linux-fsdevel@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-aio@kvack.org" , "io-uring@vger.kernel.org" , "linux-block@vger.kernel.org" , "selvakuma.s1@samsung.com" , "nj.shetty@samsung.com" References: <1592414619-5646-1-git-send-email-joshi.k@samsung.com> <1592414619-5646-4-git-send-email-joshi.k@samsung.com> <20200618083529.ciifu4chr4vrv2j5@mpHalley.local> <20200618091113.eu2xdp6zmdooy5d2@mpHalley.local> <20200619094149.uaorbger326s6yzz@mpHalley.local> <2ba2079c-9a5d-698a-a8f0-cbd6fdb9a9f0@lightnvm.io> <317fa6b5-ce64-114e-b34d-2be7b50c24f1@lightnvm.io> From: Jens Axboe Message-ID: <26f41284-6e52-58d3-6119-8ed34511e5dc@kernel.dk> Date: Fri, 19 Jun 2020 09:20:32 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <317fa6b5-ce64-114e-b34d-2be7b50c24f1@lightnvm.io> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 6/19/20 9:14 AM, Matias Bjørling wrote: > On 19/06/2020 16.18, Jens Axboe wrote: >> On 6/19/20 5:15 AM, Matias Bjørling wrote: >>> On 19/06/2020 11.41, javier.gonz@samsung.com wrote: >>>> Jens, >>>> >>>> Would you have time to answer a question below in this thread? >>>> >>>> On 18.06.2020 11:11, javier.gonz@samsung.com wrote: >>>>> On 18.06.2020 08:47, Damien Le Moal wrote: >>>>>> On 2020/06/18 17:35, javier.gonz@samsung.com wrote: >>>>>>> On 18.06.2020 07:39, Damien Le Moal wrote: >>>>>>>> On 2020/06/18 2:27, Kanchan Joshi wrote: >>>>>>>>> From: Selvakumar S >>>>>>>>> >>>>>>>>> Introduce three new opcodes for zone-append - >>>>>>>>> >>>>>>>>> IORING_OP_ZONE_APPEND : non-vectord, similiar to >>>>>>>>> IORING_OP_WRITE >>>>>>>>> IORING_OP_ZONE_APPENDV : vectored, similar to IORING_OP_WRITEV >>>>>>>>> IORING_OP_ZONE_APPEND_FIXED : append using fixed-buffers >>>>>>>>> >>>>>>>>> Repurpose cqe->flags to return zone-relative offset. >>>>>>>>> >>>>>>>>> Signed-off-by: SelvaKumar S >>>>>>>>> Signed-off-by: Kanchan Joshi >>>>>>>>> Signed-off-by: Nitesh Shetty >>>>>>>>> Signed-off-by: Javier Gonzalez >>>>>>>>> --- >>>>>>>>> fs/io_uring.c | 72 >>>>>>>>> +++++++++++++++++++++++++++++++++++++++++-- >>>>>>>>> include/uapi/linux/io_uring.h | 8 ++++- >>>>>>>>> 2 files changed, 77 insertions(+), 3 deletions(-) >>>>>>>>> >>>>>>>>> diff --git a/fs/io_uring.c b/fs/io_uring.c >>>>>>>>> index 155f3d8..c14c873 100644 >>>>>>>>> --- a/fs/io_uring.c >>>>>>>>> +++ b/fs/io_uring.c >>>>>>>>> @@ -649,6 +649,10 @@ struct io_kiocb { >>>>>>>>> unsigned long fsize; >>>>>>>>> u64 user_data; >>>>>>>>> u32 result; >>>>>>>>> +#ifdef CONFIG_BLK_DEV_ZONED >>>>>>>>> + /* zone-relative offset for append, in bytes */ >>>>>>>>> + u32 append_offset; >>>>>>>> this can overflow. u64 is needed. >>>>>>> We chose to do it this way to start with because struct io_uring_cqe >>>>>>> only has space for u32 when we reuse the flags. >>>>>>> >>>>>>> We can of course create a new cqe structure, but that will come with >>>>>>> larger changes to io_uring for supporting append. >>>>>>> >>>>>>> Do you believe this is a better approach? >>>>>> The problem is that zone size are 32 bits in the kernel, as a number >>>>>> of sectors. >>>>>> So any device that has a zone size smaller or equal to 2^31 512B >>>>>> sectors can be >>>>>> accepted. Using a zone relative offset in bytes for returning zone >>>>>> append result >>>>>> is OK-ish, but to match the kernel supported range of possible zone >>>>>> size, you >>>>>> need 31+9 bits... 32 does not cut it. >>>>> Agree. Our initial assumption was that u32 would cover current zone size >>>>> requirements, but if this is a no-go, we will take the longer path. >>>> Converting to u64 will require a new version of io_uring_cqe, where we >>>> extend at least 32 bits. I believe this will need a whole new allocation >>>> and probably ioctl(). >>>> >>>> Is this an acceptable change for you? We will of course add support for >>>> liburing when we agree on the right way to do this. >>> I took a quick look at the code. No expert, but why not use the existing >>> userdata variable? use the lowest bits (40 bits) for the Zone Starting >>> LBA, and use the highest (24 bits) as index into the completion data >>> structure? >>> >>> If you want to pass the memory address (same as what fio does) for the >>> data structure used for completion, one may also play some tricks by >>> using a relative memory address to the data structure. For example, the >>> x86_64 architecture uses 48 address bits for its memory addresses. With >>> 24 bit, one can allocate the completion entries in a 32MB memory range, >>> and then use base_address + index to get back to the completion data >>> structure specified in the sqe. >> For any current request, sqe->user_data is just provided back as >> cqe->user_data. This would make these requests behave differently >> from everything else in that sense, which seems very confusing to me >> if I was an application writer. >> >> But generally I do agree with you, there are lots of ways to make >> < 64-bit work as a tag without losing anything or having to jump >> through hoops to do so. The lack of consistency introduced by having >> zone append work differently is ugly, though. >> > Yep, agree, and extending to three cachelines is big no-go. We could add > a flag that said the kernel has changes the userdata variable. That'll > make it very explicit. Don't like that either, as it doesn't really change the fact that you're now doing something very different with the user_data field, which is just supposed to be passed in/out directly. Adding a random flag to signal this behavior isn't very explicit either, imho. It's still some out-of-band (ish) notification of behavior that is different from any other command. This is very different from having a flag that says "there's extra information in this other field", which is much cleaner. -- Jens Axboe