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=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 F0C3EC43603 for ; Thu, 12 Dec 2019 02:39:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C41EE2173E for ; Thu, 12 Dec 2019 02:39:00 +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="trZgffbq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727810AbfLLCjA (ORCPT ); Wed, 11 Dec 2019 21:39:00 -0500 Received: from mail-pg1-f195.google.com ([209.85.215.195]:45633 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727809AbfLLCi7 (ORCPT ); Wed, 11 Dec 2019 21:38:59 -0500 Received: by mail-pg1-f195.google.com with SMTP id b9so324482pgk.12 for ; Wed, 11 Dec 2019 18:38:59 -0800 (PST) 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=01GgsUaNcyRwO3k+GyWSjY6KGpQcOqatQZUk+Ajithc=; b=trZgffbqjkURsXUYXxMm3jYKaMrbMZW38hSJT/UPviKy84yDzYgXSzcnMC8RGdglk/ 7zGUibew1mhMd0qR8kTY0qfce8X9mFFoSrAAoOZLlVfEBZlxenZ7FoYFuUcOHpcNTc2K Ln5iH0oM40SRpli3ciTVAYQ+fuTz+qOSeW7J7gs6f7KovKueRaAb3yvKGN0Br5mFEhG8 83oJUMT+Iwk8TO/iPe+vNVKuVeRUeVuRNPyon9J9LrrFTc+byoXSjyqRgFG/q75VrzAM ZvMfVA6lBsL4lqtXYFpZJJ+aGAvQLVX0LHAaWiPNsvWLHi97j6rzuoPICDo+i6jqnWR2 SAYg== 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=01GgsUaNcyRwO3k+GyWSjY6KGpQcOqatQZUk+Ajithc=; b=erBl7A2Z8Dq3gBRnX/5h1FN8I4T7uHjkJbF2CoFPcCqR1WDPpejyxI90s8XYO9SqaK fHjgAT+POrWmCUMkncGnWOqNqbboCDX5kBbrJx/HSb9tZF2cImB9DQuAWvPnqdN6JdJw rtWGNiyRy9PRWKBbBF8rosJA90k2xoucadxaP/HFO+T45qJMkH85F3lLyRdIWv1oBNmF pm4uvTEfzn5j2l/6So4y0hRlHNkC0epBSEmhOsLr1B093r55udoeB2F8GIovODCowMUF 8321XYlnRrfsh+A0yRrtaglF1oNOgNHLuEOWDKYgr9Jf0bTjlg6wO1E7jf3jWnpsIvaN bBXA== X-Gm-Message-State: APjAAAXIlKLgPm6o86tzj0tm0PGmMmEo6GcxSaRL5A245u5q5QK14BU1 0mj+FLiA2P7paFnmMSOQgC3r8A== X-Google-Smtp-Source: APXvYqwe/Bd+rMaHYLrn8alwGVoil0g0wm0EcnCYa8dkFYiQA1xf7NCuqkGKl/1J3tGSKHHN2WyU7g== X-Received: by 2002:a63:541e:: with SMTP id i30mr7679631pgb.183.1576118338884; Wed, 11 Dec 2019 18:38:58 -0800 (PST) Received: from ?IPv6:2620:10d:c081:1131::1082? ([2620:10d:c090:180::628a]) by smtp.gmail.com with ESMTPSA id g9sm4810073pfm.150.2019.12.11.18.38.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 11 Dec 2019 18:38:57 -0800 (PST) Subject: Re: [PATCHSET v3 0/5] Support for RWF_UNCACHED To: Matthew Wilcox Cc: Linus Torvalds , Linux-MM , linux-fsdevel , linux-block , Chris Mason , Dave Chinner , Johannes Weiner References: <20191211152943.2933-1-axboe@kernel.dk> <0d4e3954-c467-30a7-5a8e-7c4180275533@kernel.dk> <00a5c8b7-215a-7615-156d-d8f3dbb1cd3a@kernel.dk> <20191212022155.GQ32169@bombadil.infradead.org> From: Jens Axboe Message-ID: <9269b4e0-829c-8b95-61ff-f3922c6380f6@kernel.dk> Date: Wed, 11 Dec 2019 19:38:54 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20191212022155.GQ32169@bombadil.infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 12/11/19 7:21 PM, Matthew Wilcox wrote: > On Wed, Dec 11, 2019 at 07:03:40PM -0700, Jens Axboe wrote: >> Tested and cleaned a bit, and added truncate protection through >> inode_dio_begin()/inode_dio_end(). >> >> https://git.kernel.dk/cgit/linux-block/commit/?h=buffered-uncached&id=6dac80bc340dabdcbfb4230b9331e52510acca87 >> >> This is much faster than the previous page cache dance, and I _think_ >> we're ok as long as we block truncate and hole punching. > > What about races between UNCACHED and regular buffered IO? Seems like > we might end up sending overlapping writes to the device? The UNCACHED out-of-page-cache IO is just for reads, it's not writes. The write part is still using the same approach as earlier, though now I bet it looks kinda slow compared to the read side... -- Jens Axboe