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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B138DC433F5 for ; Fri, 20 May 2022 15:47:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351113AbiETPr0 (ORCPT ); Fri, 20 May 2022 11:47:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47706 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242225AbiETPqz (ORCPT ); Fri, 20 May 2022 11:46:55 -0400 Received: from mail-pf1-x42b.google.com (mail-pf1-x42b.google.com [IPv6:2607:f8b0:4864:20::42b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 921FA5F24A for ; Fri, 20 May 2022 08:46:35 -0700 (PDT) Received: by mail-pf1-x42b.google.com with SMTP id v11so8083754pff.6 for ; Fri, 20 May 2022 08:46:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=eGcTsYf8iVYg1xNbI/fjMVaCB61SkbZVpEsdDGyPSy0=; b=O3dHH+ATXMsS3gQnUfEVaqgUE+ermYGggTUHL/hAVkMdgfyYYDAjaWikrTtY8Pp6wv tKFi8ZueYqcPc4eFrrXc4uCTH493zHH9FnzLoesCAI44fVDbalDN9flwCdDcqONnW48v dD7jmZALIj+LdxHUY+y1MjnaUye6KzBB8pON/3JDIWRhmep1YNJP5KWjdSbRKuxIaQO1 ohVGnAbXYgoT572WMvnwbb6kGCCeKoX6cvVKtnY7FOOBFwIC37HkB4Qyb1WSOBELIj1R Ij1iYPfz1nRgXKS53Xmlowq/ZySPq/pt4PV75itOgKk4bZhRXi7Fl9SwL0crKwT2Fop3 5hjQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=eGcTsYf8iVYg1xNbI/fjMVaCB61SkbZVpEsdDGyPSy0=; b=7/adZuX/dqUoRU3GHzc4ocCkH4p8saOmlBaYgFf0VzQrFyNmuwJOtOD0F/xOIt8Ivt Sk0BC9u2B0diVAcqLS/mtYiEJ3IoxYl+tL5nTD76bX/7vU3tvcWf+mSKk9Ms+5pbLcA6 kbFwylxSVG+g5cbFQoiMj5j4zjB4H70uPs0qrov7ecFgZ/qVPAlyPYIwgJoBn3ab4ga8 luZGfbVyFHCEOBmGCA9cR3SJ16uLy0ycA9G8ZBvcFbV9WxxG08GhGNzSruvrQMDcKWCQ ssM6Twm1PyRcLrsf2K69mEeWcq5tdZ/S7WswWo+rLvc04MbQiaE3BEFYOJGldl8MXBat q0gg== X-Gm-Message-State: AOAM532+vui4aHCIwCChtHrWvyaAiAhS/vsdejvOJG3d7Gn9b3aNWQIz ADoHSBQUw2jPaZ+QeOHRX3jXVw== X-Google-Smtp-Source: ABdhPJyHVDi3GkJibJeCyTDG61Y7KGHWoET2M+t/bVmUBSUfXB+PE2IKO4OB8WgcSATs6LuAkF0mDQ== X-Received: by 2002:a63:455e:0:b0:3c6:270f:cec4 with SMTP id u30-20020a63455e000000b003c6270fcec4mr8885229pgk.417.1653061594803; Fri, 20 May 2022 08:46:34 -0700 (PDT) Received: from [192.168.1.100] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id y1-20020a1709027c8100b0015e8d4eb263sm5737536pll.173.2022.05.20.08.46.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 20 May 2022 08:46:34 -0700 (PDT) Message-ID: Date: Fri, 20 May 2022 09:46:33 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH] char/mem: only use {read,write}_iter, not the old {read,write} functions Content-Language: en-US To: Al Viro Cc: "Jason A. Donenfeld" , gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org References: <20220520135030.166831-1-Jason@zx2c4.com> From: Jens Axboe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/20/22 9:44 AM, Al Viro wrote: > On Fri, May 20, 2022 at 09:32:34AM -0600, Jens Axboe wrote: > >> Didn't look closer, but I'm assuming this is _mostly_ tied to needing to >> init 48 bytes of kiocb for each one. There might be ways to embed a >> sync_kiocb inside the kiocb for the bits we need there, at least that >> could get us down to 32 bytes. > > My bet would be on iocb_flags() (and kiocb_set_rw_flags()) tests and > pointer-chasing, actually. That would be my guess too, around init/setup of the kiocb. But as per previous email, for some reason it seems _worse_ on bigger reads (1k and 4k vs 32 bytes), which would seem to indicate that it's not necessarily just the setup but something else too. And hopefully that "something else" is workable. > I'd been sick on and off since early November, trying to dig myself > from under the piles right now. Christoph's patches in that area are > somewhere in the pile ;-/ Sorry to hear that, hope you're feeling better. Do you have a pointer to those patches? -- Jens Axboe