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 69020C433F5 for ; Fri, 20 May 2022 15:34:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350893AbiETPex (ORCPT ); Fri, 20 May 2022 11:34:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243036AbiETPeu (ORCPT ); Fri, 20 May 2022 11:34:50 -0400 Received: from mail-pg1-x535.google.com (mail-pg1-x535.google.com [IPv6:2607:f8b0:4864:20::535]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 39A93179084 for ; Fri, 20 May 2022 08:34:49 -0700 (PDT) Received: by mail-pg1-x535.google.com with SMTP id r71so8066736pgr.0 for ; Fri, 20 May 2022 08:34:49 -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 :references:from:in-reply-to:content-transfer-encoding; bh=e3zRTRtgvILEICGPiLa/WYEa5fM29ZCSz7EUFRvdtTU=; b=oGkNhLX3ZdPbv/FoolRZwwzMYLvSflVnMKZndrubwwVxefDL/TJsFcwA7PHv3NPmop 1AjRtWBBvEnjh5/Hz5IT6vr880lfZw2A02pAcAcrssPEWPQm+BfkFrNZgqPu+pOgqZNI 5//sCsv6kGtH1fLbFATDm0TD4qVmx936MlA8s+V9XKNR72F5kWuYpZAskohh3Ll9URu0 5wAIPJ6ZsufyrR/wE7C3HSYq74VRIRgH8Mlrv3yercHpUNtj7yt5kexMM5Pd12uPcLv8 oxQiynEUoCRcvOF84+EE8T46bpi5LD2PvABqt1I3iezIB50wrHQW2uHMYWqrFEzgtXSh Z6xA== 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:references:from:in-reply-to :content-transfer-encoding; bh=e3zRTRtgvILEICGPiLa/WYEa5fM29ZCSz7EUFRvdtTU=; b=whtJ3/NfnYPa1JBV6UsQ6suBip3Co9+YvaH1Mys2tLN2ljD+4peLrLq4rw5MVqb1UX I4Gc7gZ5JsdXH9TfXYuE+j0R1LyhUCY78LAqBa8gmeZmAxqAjh1HBOQpKuqaQVHjx//5 H8OSZ1Ikg3GAiK4Oh0NlpCOYFLQ7x09PqhJ8/N7MkfP9e8r0bcgCKwQSGUs6/qSMOpy1 mq1Cmr1rpe7FZ4cmtOwMuJ5+74ZWDvgILSDvIyzcKFXiV++odeNorsHNqThTCm3bFThl i1YKkbIbdLgggt8xyYBKqZixys9Cl86a0HQY84Xf5IfRL+klhS/hXrY/69KrNGQsuQMN NYZw== X-Gm-Message-State: AOAM532aZzS4vJkgpYeQslR+Y62pIrZ+besFHKa3WE6d0FTsm5ED27+Y e+QIkUxyTZo3WYkDz6w2F4uceQ== X-Google-Smtp-Source: ABdhPJye3iSjVZVnCNjKkjVoudazo5xjF4r6gxTAf/5wgpCjyoSqMp8Kyzng+oax8HnxSmv5B37mqA== X-Received: by 2002:a63:115b:0:b0:3c1:eb46:6f5 with SMTP id 27-20020a63115b000000b003c1eb4606f5mr9021128pgr.277.1653060888405; Fri, 20 May 2022 08:34:48 -0700 (PDT) Received: from [192.168.1.100] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id l13-20020a17090af8cd00b001cd4989ff42sm2029545pjd.9.2022.05.20.08.34.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 20 May 2022 08:34:47 -0700 (PDT) Message-ID: Date: Fri, 20 May 2022 09:34:46 -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 v4 0/3] random: convert to using iters, for Al Viro Content-Language: en-US To: "Jason A. Donenfeld" , Theodore Ts'o , Christoph Hellwig , LKML , Al Viro References: <20220520094459.116240-1-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 9:25 AM, Jason A. Donenfeld wrote: > Hi Jens, > > On Fri, May 20, 2022 at 11:44:56AM +0200, Jason A. Donenfeld wrote: >> Jens Axboe (3): >> random: convert to using fops->read_iter() >> random: convert to using fops->write_iter() >> random: wire up fops->splice_{read,write}_iter() > > FYI, this series makes reads from /dev/urandom slower, from around 616 > MiB/s to 598 MiB/s on my system. That seems rather unfortunate. How reproducible is that? That seems like a huge difference for the change. How big are the reads? > Are we sure we really want to do this and need to do this? I'm very sure, otherwise we're just accepting that we're breaking real world applications. Alternatively, you can keep the ->read() and add the ->read_iter() as well, but I'm a bit skeptical at your initial results there. -- Jens Axboe