From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by sourceware.org (Postfix) with ESMTPS id 92960383D011 for ; Tue, 8 Jun 2021 13:27:36 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 92960383D011 Received: by mail.kernel.org (Postfix) with ESMTPSA id EBA3E61009; Tue, 8 Jun 2021 13:27:34 +0000 (UTC) Date: Tue, 8 Jun 2021 15:27:32 +0200 From: Greg KH To: Andrey Semashev Cc: Nicholas Piggin , =?iso-8859-1?Q?Andr=E9?= Almeida , acme@kernel.org, Sebastian Andrzej Siewior , corbet@lwn.net, Davidlohr Bueso , Darren Hart , fweimer@redhat.com, joel@joelfernandes.org, kernel@collabora.com, krisman@collabora.com, libc-alpha@sourceware.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, malteskarupke@fastmail.fm, Ingo Molnar , Peter Zijlstra , pgriffais@valvesoftware.com, Peter Oskolkov , Steven Rostedt , shuah@kernel.org, Thomas Gleixner , z.figura12@gmail.com Subject: Re: [PATCH v4 00/15] Add futex2 syscalls Message-ID: References: <1622853816.mokf23xgnt.astroid@bobo.none> <6d8e3bb4-0cef-b991-9a16-1f03d10f131d@gmail.com> <1622980258.cfsuodze38.astroid@bobo.none> <1623114630.pc8fq7r5y9.astroid@bobo.none> <8fa8b7fd-58ae-9467-138d-4ff4f32f68f7@gmail.com> <3fca0afa-d9db-a176-aad1-ff7db21ba4a2@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3fca0afa-d9db-a176-aad1-ff7db21ba4a2@gmail.com> X-Spam-Status: No, score=-3.1 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 08 Jun 2021 13:27:37 -0000 On Tue, Jun 08, 2021 at 04:18:42PM +0300, Andrey Semashev wrote: > On 6/8/21 3:35 PM, Greg KH wrote: > > On Tue, Jun 08, 2021 at 03:06:48PM +0300, Andrey Semashev wrote: > > > On 6/8/21 2:13 PM, Greg KH wrote: > > > > > > So what's keeping the futex2 code from doing all that futex1 does so > > > > that the futex1 code can be deleted internally? > > > > > > I think, André will answer this, but my guess is, as stated above, this is a > > > lot of work and time while the intermediate version is already useful. > > > > useful to who? I still do not understand what users will be needing > > this. All I can tell is a single userspace program wants to use it, and > > that is a fork from the real project it was based on and that the > > maintainers have no plan to merge it back. > > > > So who does need/want this? > > I mentioned C++ std::atomic and Boost.Atomic before. Those need variable > sized futexes. And has anyone converted them to use this new api to see if it works well or not? As was pointed out to me numerous times when I tried to propose readfile(), you need a real user that can show and prove it is needed before we can take new syscalls, especially complex beasts like this one. thanks, greg k-h