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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AC15CC433F5 for ; Tue, 12 Oct 2021 14:47:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 934B06108F for ; Tue, 12 Oct 2021 14:47:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237092AbhJLOth (ORCPT ); Tue, 12 Oct 2021 10:49:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237186AbhJLOtd (ORCPT ); Tue, 12 Oct 2021 10:49:33 -0400 Received: from mail-il1-x135.google.com (mail-il1-x135.google.com [IPv6:2607:f8b0:4864:20::135]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 44D40C061745 for ; Tue, 12 Oct 2021 07:47:31 -0700 (PDT) Received: by mail-il1-x135.google.com with SMTP id x1so8396829ilv.4 for ; Tue, 12 Oct 2021 07:47:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=4MJaMMW8746DQT1wOfh06NFmp8vY5yRZAB/PDHHSeGY=; b=wOIbilVM5gc/k/LZ9/Ir1wHPCDEC+IR+oeQmi8pjQTvUyvfa2oZbSfQqPDImNMgtyQ DxhGgaz5+RPNRuFubDCiRCMnZceDLrc+C4OB89sWzEOWrTG+y91hDngiR3YIKZ+/aVH/ 9Bii7ghXtllIvrSjzGpTWpaI1pJURBqQbV6hd8+09Ufn95OxlNx5YjjsjiyT5oglv1Xe ToMkqjYZp0OudBD2QdC/8exoIwens1dkP4DGoLp6RebMGZTeOkDN3LAr6NIZDEU1VHWS PvyzkvQuSb/1CIei/9oaMldCHe344kFIwyg0rEFoGlgBAJfyJh0Q+Lx1Q2O/iSyAVSfO sxjQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; 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=4MJaMMW8746DQT1wOfh06NFmp8vY5yRZAB/PDHHSeGY=; b=TntydvXo79QGTtXwf7c5NmQx0INtRohQO6Tzf4b/2h+PlEmqXllq3/dvkGubrzk/ne +/zcQkCoRx3FVaNYT1fA2t+qjHE1a7yk/lNDMq/xqm0c5qknvRvtpqFypDIXJJHFx9YF Naz3/Gde8r7xIEz2UAecoUV7H004E8IXGzNIBpZBhyOxaZRRfre7u3Vl6G2JDFylhyHt XY9159Lh/vbkZvYJY9somvpeLooApooSbuXI/GLxz+fa2ZzlmsmfEaTZBNZAfhgL/nNj indIIZPXLgPsYbjAc4rPLvOCuyccBIr45D9WJ7xpbbhGp1u5aoJ7JeivOr9gzIQEiQah 5/sQ== X-Gm-Message-State: AOAM530OCZcBOamfp+/4nftaygH03LB70UTKe5ls4o1eTIx4MePZsArN JcsYlrSuAjcWORnkcdQYxRfFGg== X-Google-Smtp-Source: ABdhPJxapnRy6JleZezPqu6pNBbq7PwR7Um8itvadPDoYS1xyG7UZ+W6d1/blh57xUyZyd+hWUDWDg== X-Received: by 2002:a05:6e02:160a:: with SMTP id t10mr23554089ilu.207.1634050050606; Tue, 12 Oct 2021 07:47:30 -0700 (PDT) Received: from [192.168.1.30] ([207.135.234.126]) by smtp.gmail.com with ESMTPSA id 2sm5337003iob.13.2021.10.12.07.47.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Oct 2021 07:47:30 -0700 (PDT) Subject: Re: switch block layer polling to a bio based model v4 To: Christoph Hellwig Cc: Jeffle Xu , Ming Lei , Damien Le Moal , Keith Busch , Sagi Grimberg , "Wunderlich, Mark" , "Vasudevan, Anil" , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nvme@lists.infradead.org References: <20211012111226.760968-1-hch@lst.de> From: Jens Axboe Message-ID: <07f31547-5570-4150-7a4b-1d773fb9fa87@kernel.dk> Date: Tue, 12 Oct 2021 08:47:29 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20211012111226.760968-1-hch@lst.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 10/12/21 5:12 AM, Christoph Hellwig wrote: > Hi all, > > This series clean up the block polling code a bit and changes the interface > to poll for a specific bio instead of a request_queue and cookie pair. > > Polling for the bio itself leads to a few advantages: > > - the cookie construction can made entirely private in blk-mq.c > - the caller does not need to remember the request_queue and cookie > separately and thus sidesteps their lifetime issues > - keeping the device and the cookie inside the bio allows to trivially > support polling BIOs remapping by stacking drivers > - a lot of code to propagate the cookie back up the submission path can > removed entirely > > The one major caveat is that this requires RCU freeing polled BIOs to make > sure the bio that contains the polling information is still alive when > io_uring tries to poll it through the iocb. For synchronous polling all the > callers have a bio reference anyway, so this is not an issue. I ran this through the usual peak testing, and it doesn't seem to regress anything for me. We're still at around ~7.4M polled IOPS on a single CPU core: taskset -c 0,16 t/io_uring -d128 -b512 -s32 -c32 -p1 -F1 -B1 -D1 -n2 /dev/nvme1n1 /dev/nvme2n1 Added file /dev/nvme1n1 (submitter 0) Added file /dev/nvme2n1 (submitter 1) polled=1, fixedbufs=1, register_files=1, buffered=0, QD=128 Engine=io_uring, sq_ring=128, cq_ring=256 submitter=0, tid=1199 submitter=1, tid=1200 IOPS=7322112, BW=3575MiB/s, IOS/call=32/31, inflight=(110 71) IOPS=7452736, BW=3639MiB/s, IOS/call=32/31, inflight=(52 80) IOPS=7419904, BW=3623MiB/s, IOS/call=32/31, inflight=(78 104) IOPS=7392576, BW=3609MiB/s, IOS/call=32/32, inflight=(75 102) with some of my pending changes and hacks. Using IRQ mode, we're at around 4.9M and I don't see any particular impact of needing deferred RCU free of the bio for that case. -- Jens Axboe