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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 D0323C433DF for ; Sat, 4 Jul 2020 19:30:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA19320890 for ; Sat, 4 Jul 2020 19:30:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727118AbgGDTaq (ORCPT ); Sat, 4 Jul 2020 15:30:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56236 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726643AbgGDTaq (ORCPT ); Sat, 4 Jul 2020 15:30:46 -0400 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EE122C061794; Sat, 4 Jul 2020 12:30:45 -0700 (PDT) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jrns0-005NRw-HY; Sat, 04 Jul 2020 19:30:40 +0000 Date: Sat, 4 Jul 2020 20:30:40 +0100 From: Al Viro To: Greg Kroah-Hartman Cc: mtk.manpages@gmail.com, shuah@kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-man@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH 0/3] readfile(2): a new syscall to make open/read/close faster Message-ID: <20200704193040.GC2786714@ZenIV.linux.org.uk> References: <20200704140250.423345-1-gregkh@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200704140250.423345-1-gregkh@linuxfoundation.org> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Sat, Jul 04, 2020 at 04:02:46PM +0200, Greg Kroah-Hartman wrote: > Here is a tiny new syscall, readfile, that makes it simpler to read > small/medium sized files all in one shot, no need to do open/read/close. > This is especially helpful for tools that poke around in procfs or > sysfs, making a little bit of a less system load than before, especially > as syscall overheads go up over time due to various CPU bugs being > addressed. Nice series, but you are 3 months late with it... Next AFD, perhaps? Seriously, the rationale is bollocks. If the overhead of 2 extra syscalls is anywhere near the costs of the real work being done by that thing, we have already lost and the best thing to do is to throw the system away and start with saner hardware.