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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 24476C3F2D1 for ; Thu, 5 Mar 2020 16:25:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EB90E208CD for ; Thu, 5 Mar 2020 16:25:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ToEOOt4l" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726099AbgCEQZm (ORCPT ); Thu, 5 Mar 2020 11:25:42 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:20717 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725963AbgCEQZm (ORCPT ); Thu, 5 Mar 2020 11:25:42 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1583425541; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=upBJ1YaaDvvizCIJlD7zDa27JX49RWsGRLEsXBieMeU=; b=ToEOOt4lwDiZOg+Ly3C+UgSxTXRxtg7t8MhwUgr/GTbwteEmaTBIqhA2TaHXlWcXXF+A5/ 3YmBOJQzDytnYxjbJndBr1jc0yp9Ep7p7r5Mg90YP9y7SqQjdzQUtceQobpDgme62/C0Ad 2zJOPXwQkMHQ22Ph+j8hkJjTG4WuiTQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-274-5tI_py84MuaSwXH-EahB0Q-1; Thu, 05 Mar 2020 11:25:37 -0500 X-MC-Unique: 5tI_py84MuaSwXH-EahB0Q-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EE5D6800D4E; Thu, 5 Mar 2020 16:25:34 +0000 (UTC) Received: from oldenburg2.str.redhat.com (ovpn-116-226.ams2.redhat.com [10.36.116.226]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E2F7B73893; Thu, 5 Mar 2020 16:25:25 +0000 (UTC) From: Florian Weimer To: =?utf-8?Q?Andr=C3=A9?= Almeida Cc: Peter Zijlstra , "Pierre-Loup A. Griffais" , Thomas Gleixner , linux-kernel@vger.kernel.org, kernel@collabora.com, krisman@collabora.com, shuah@kernel.org, linux-kselftest@vger.kernel.org, rostedt@goodmis.org, ryao@gentoo.org, dvhart@infradead.org, mingo@redhat.com, z.figura12@gmail.com, steven@valvesoftware.com, steven@liquorix.net, malteskarupke@web.de, carlos@redhat.com, adhemerval.zanella@linaro.org, libc-alpha@sourceware.org, linux-api@vger.kernel.org Subject: Re: 'simple' futex interface [Was: [PATCH v3 1/4] futex: Implement mechanism to wait on any of several futexes] References: <20200228190717.GM18400@hirez.programming.kicks-ass.net> <20200228194958.GO14946@hirez.programming.kicks-ass.net> <87tv3aflqm.fsf@nanos.tec.linutronix.de> <967d5047-2cb6-d6d8-6107-edb99a4c9696@valvesoftware.com> <87o8thg031.fsf@nanos.tec.linutronix.de> <20200303120050.GC2596@hirez.programming.kicks-ass.net> <87pndth9ur.fsf@oldenburg2.str.redhat.com> <20200303132150.GD2596@hirez.programming.kicks-ass.net> <878skhh7og.fsf@oldenburg2.str.redhat.com> <20200303150104.GE2596@hirez.programming.kicks-ass.net> <52406c54-60b3-dcfe-65d8-4c425459e37b@collabora.com> Date: Thu, 05 Mar 2020 17:25:23 +0100 In-Reply-To: <52406c54-60b3-dcfe-65d8-4c425459e37b@collabora.com> (=?utf-8?Q?=22Andr=C3=A9?= Almeida"'s message of "Thu, 5 Mar 2020 13:14:17 -0300") Message-ID: <87imji7or0.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org * Andr=C3=A9 Almeida: > Thanks everyone for the feedback around our mechanism. Are the > performance benefits of implementing a syscall to wait on a single futex > significant enough to maintain it instead of just using > `sys_futex_waitv()` with `nr_waiters =3D 1`? If we join both cases in a > single interface, we may even add a new member for NUMA hint in `struct > futex_wait`. Some seccomp user might want to verify the address, and that's easier if it's in an argument. But that's just a rather minor aspect. Do you propose to drop the storage requirement for the NUMA hint next to the futex completely? Thanks, Florian