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=-4.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 444FDC4320A for ; Sat, 7 Aug 2021 10:08:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 192216115C for ; Sat, 7 Aug 2021 10:08:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231760AbhHGKGj (ORCPT ); Sat, 7 Aug 2021 06:06:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35382 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230090AbhHGKG2 (ORCPT ); Sat, 7 Aug 2021 06:06:28 -0400 Received: from mail-wr1-x42c.google.com (mail-wr1-x42c.google.com [IPv6:2a00:1450:4864:20::42c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A967BC0613CF; Sat, 7 Aug 2021 03:06:08 -0700 (PDT) Received: by mail-wr1-x42c.google.com with SMTP id m12so14349532wru.12; Sat, 07 Aug 2021 03:06:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=Ut8/KNFRFcQqrLccjjc1Iq2etNteCks1XWkqaFKEZy0=; b=usi62ZFLaki5oyxywr3g0oprkNmlVIlS1H1gE73a/Z4cuFIRtTU9jPCg5K3BcJ6mK0 5Y6EA1+EBznKCDRZbgGFvuxOL/gpT0tgkca3LLsox4bvCYDZhRpT7+r/8mGNqAXON6Ij 65BxU2JbSzwid15FD3gCSajZ7mZhMDc9Te2VYBYMvgbEKBf9v+RbAUBpCZn0XUHdSLD5 Lm9NoMxxBG1nbjmTXcQlZzgwK5wUKxeg5U0msxD5/e0GMpgBTrSsi8bLrcwRsM+ikBz/ zpPiYNBdPHv0k3vj4DuO55jt8aTHz4R+ah0fNHJubybGTLdUgtiTZ/BXt48upN2hmnEy Unmg== 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=Ut8/KNFRFcQqrLccjjc1Iq2etNteCks1XWkqaFKEZy0=; b=Ro0U4/AMp1vsKCUTxmFBMa+6f87pB/W2yxhSk4InteCjIoQxJCnuuqg4XOSCfazLYZ 8WUqQ2AGG+pgZp1olOXDLhk8ZK2SfYUyNDeA7QGxUD/heXCahDhWz+9ba/2xKHah7dgK Wt+Jil3VbuxD14yogA5BiNB2epwqNr7Bo5s1cHCpOaJuv71FDJQK/0KibnupKyN+81+k S3VhC6GKolnw5NpCYXZuiordi2XRCVYyldhXdyaIlxVxSUvKQ/PMbL2zUeFQoLVFPRLv IYYqJPWgTbmfrF0yOjaPq88kWD5KoJljgcvsSeTeEsb0VuesOrPLi/wU7fSbX5grP6d3 q2xw== X-Gm-Message-State: AOAM533Q+dvCFH4ByDzoh9Ta7h/vF2/6HeJrTNsBC4ZgTMk8QgaG9L/u 6LkE0/WITL5z8IkKKMjQkh0dvUw/egs= X-Google-Smtp-Source: ABdhPJx7/Of4aEYxyifIy6jnxnLfkit5KMnvUSb3piLbfc6HaMxZ9HglfAqpPChs3qGvX7PpMH7qHw== X-Received: by 2002:a05:6000:1106:: with SMTP id z6mr15440031wrw.296.1628330767119; Sat, 07 Aug 2021 03:06:07 -0700 (PDT) Received: from [192.168.8.197] ([85.255.237.206]) by smtp.gmail.com with ESMTPSA id w14sm1425505wrt.23.2021.08.07.03.06.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 07 Aug 2021 03:06:06 -0700 (PDT) Subject: Re: [PATCH] fs: optimise generic_write_check_limits() To: Matthew Wilcox Cc: Alexander Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: From: Pavel Begunkov Message-ID: Date: Sat, 7 Aug 2021 11:05:38 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 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-kernel@vger.kernel.org On 8/6/21 2:28 PM, Matthew Wilcox wrote: > On Fri, Aug 06, 2021 at 12:22:10PM +0100, Pavel Begunkov wrote: >> Even though ->s_maxbytes is used by generic_write_check_limits() only in >> case of O_LARGEFILE, the value is loaded unconditionally, which is heavy >> and takes 4 indirect loads. Optimise it by not touching ->s_maxbytes, >> if it's not going to be used. > > Is this "optimisation" actually worth anything? Look at how > force_o_largefile() is used. I would suggest that on the vast majority > of machines, O_LARGEFILE is always set. Makes sense to leave it alone then, thanks -- Pavel Begunkov