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 748F3C433EF for ; Thu, 11 Nov 2021 00:26:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C85D61251 for ; Thu, 11 Nov 2021 00:26:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232271AbhKKA33 (ORCPT ); Wed, 10 Nov 2021 19:29:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37688 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232515AbhKKA3Z (ORCPT ); Wed, 10 Nov 2021 19:29:25 -0500 Received: from mail-io1-xd33.google.com (mail-io1-xd33.google.com [IPv6:2607:f8b0:4864:20::d33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D5D5EC06127A for ; Wed, 10 Nov 2021 16:26:36 -0800 (PST) Received: by mail-io1-xd33.google.com with SMTP id x10so4915158ioj.9 for ; Wed, 10 Nov 2021 16:26:36 -0800 (PST) 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=NyY8bek2WvSGjibqw1QUPQDNaQc/2Apt9v2sF1q2Sv4=; b=jl8dCUt7BkCW8ACewdF5osqNI3RRnyRBlDQP+bydLnpGYyQGl6gpUQLfxoxQoh5i6V MZBsAXng179VNrfxCM39UGTAJvAJ4/yuK9LxptVUGrVjXh3EuNxWp9CPHDp5/qxXAbUK AudU9T1bq4PRSE2Xwcu3+vNRsTRrmfqH8pR7ojn4yKH28l7o9Ysq8/kenSprv+E4r+tD hQUx6HWhvEGAk2z+k4uH1bSjsGBesfOspT7wG/rmpTeAvbpPyEVeGUSveLIw56fx3Ifo saZYwZiQsc5w+jWXEoA7zR3Kg8fblBc4BMesHGNlJs+5LBQVWbMdqOH4gO1jHXW8FIoB t+Vg== 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=NyY8bek2WvSGjibqw1QUPQDNaQc/2Apt9v2sF1q2Sv4=; b=X2/hRU4FX8rc0+kZS4bOaGFrBP/tvXVPa+07/4BjFBHAgFQAtvQ7RJT6ERsMHn+tjB 9E+YRUMMkuqi6I8HXfkKmkCm4BLS0+DkK7Z9/3ZXfTR/VW7rmwcpug7F6qV4Uxrta3BT LcZrFAsnSAs9MNaayzEXreBqe0Z9TvHIL7ql4Qv10JNMpILyC11afZzbUhqRQczCmQfi 9fHz1Gm3/JM8oP0dPMWlzS4v5ffQmy5gmD43+L0Vg4uf4ji0W6Ap32PO4b/KsoxsGRRe 1TDCT9v19exCpKZXw+6ovrL0+R9WmHhMhY0V+XJeL1LyDHeQ5pxWkdRjgS6HkeSd2a6k B4GQ== X-Gm-Message-State: AOAM5321r23gTp1YrvpxRjLRBBRnWxYvSNUk3qM21XB8gW7OmuaurtBK NyraXXVa2AaPWN33+6VIFfKgUw== X-Google-Smtp-Source: ABdhPJxopWi9rf1i9qBVVWTcqIkAhArpHV5fNVB3eoBbngZouc4tphuIfKJZ6Q5OY/IaBbXy3Iy8rw== X-Received: by 2002:a5d:8903:: with SMTP id b3mr2207722ion.44.1636590396221; Wed, 10 Nov 2021 16:26:36 -0800 (PST) Received: from [192.168.1.116] ([66.219.217.159]) by smtp.gmail.com with ESMTPSA id s15sm1139630ilu.16.2021.11.10.16.26.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 10 Nov 2021 16:26:35 -0800 (PST) Subject: Re: [PATCH] f2fs: provide a way to attach HIPRI for Direct IO To: Jaegeuk Kim Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <20211109021336.3796538-1-jaegeuk@kernel.org> <042997ce-8382-40fe-4840-25f40a84c4bf@kernel.dk> From: Jens Axboe Message-ID: Date: Wed, 10 Nov 2021 17:26:35 -0700 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: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 11/10/21 12:08 PM, Jaegeuk Kim wrote: > On 11/09, Jens Axboe wrote: >> On 11/9/21 9:39 AM, Christoph Hellwig wrote: >>> On Mon, Nov 08, 2021 at 06:13:36PM -0800, Jaegeuk Kim wrote: >>>> This patch adds a way to attach HIPRI by expanding the existing sysfs's >>>> data_io_flag. User can measure IO performance by enabling it. >>> >>> NAK. This flag should only be used when explicitly specified by >>> the submitter of the I/O. >> >> Yes, this cannot be set in the middle for a multitude of reasons. I wonder >> if we should add a comment to that effect near the definition of it. > > Not surprising. I was wondering we can add this for testing purpose only. > Btw, is there a reasonable way that filesystem can use IO polling? Whether an IO is polled or not belongs to the issuer of the IO, as it comes with certain obligations like "I will actively poll for the completion of this request", and it incurs certain restrictions in the block layer in terms of whether or not you can ever sleep for requests. You could certainly use in in an fs, but only IFF you are the original issuer of the request, which then also means that you are the one that needs to poll for completion of it. It's not a drive-by "let's set this flag to speed things up" kind of flag, there are a lot more moving parts than that. I don't think it will be useful for you. -- Jens Axboe 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 6E5DAC433EF for ; Thu, 11 Nov 2021 00:26:54 +0000 (UTC) Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1D13E6124D; Thu, 11 Nov 2021 00:26:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 1D13E6124D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.sourceforge.net Received: from [127.0.0.1] (helo=sfs-ml-2.v29.lw.sourceforge.com) by sfs-ml-2.v29.lw.sourceforge.com with esmtp (Exim 4.94.2) (envelope-from ) id 1mkxvX-0004Ov-HZ; 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Wed, 10 Nov 2021 16:26:36 -0800 (PST) Received: from [192.168.1.116] ([66.219.217.159]) by smtp.gmail.com with ESMTPSA id s15sm1139630ilu.16.2021.11.10.16.26.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 10 Nov 2021 16:26:35 -0800 (PST) To: Jaegeuk Kim References: <20211109021336.3796538-1-jaegeuk@kernel.org> <042997ce-8382-40fe-4840-25f40a84c4bf@kernel.dk> From: Jens Axboe Message-ID: Date: Wed, 10 Nov 2021 17:26:35 -0700 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: Content-Language: en-US X-Headers-End: 1mkxvN-0092b6-U7 Subject: Re: [f2fs-dev] [PATCH] f2fs: provide a way to attach HIPRI for Direct IO X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Christoph Hellwig , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On 11/10/21 12:08 PM, Jaegeuk Kim wrote: > On 11/09, Jens Axboe wrote: >> On 11/9/21 9:39 AM, Christoph Hellwig wrote: >>> On Mon, Nov 08, 2021 at 06:13:36PM -0800, Jaegeuk Kim wrote: >>>> This patch adds a way to attach HIPRI by expanding the existing sysfs's >>>> data_io_flag. User can measure IO performance by enabling it. >>> >>> NAK. This flag should only be used when explicitly specified by >>> the submitter of the I/O. >> >> Yes, this cannot be set in the middle for a multitude of reasons. I wonder >> if we should add a comment to that effect near the definition of it. > > Not surprising. I was wondering we can add this for testing purpose only. > Btw, is there a reasonable way that filesystem can use IO polling? Whether an IO is polled or not belongs to the issuer of the IO, as it comes with certain obligations like "I will actively poll for the completion of this request", and it incurs certain restrictions in the block layer in terms of whether or not you can ever sleep for requests. You could certainly use in in an fs, but only IFF you are the original issuer of the request, which then also means that you are the one that needs to poll for completion of it. It's not a drive-by "let's set this flag to speed things up" kind of flag, there are a lot more moving parts than that. I don't think it will be useful for you. -- Jens Axboe _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel