From owner-freebsd-threads@FreeBSD.ORG Mon Dec 28 16:37:08 2009 Return-Path: Delivered-To: freebsd-threads@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 97F1F1065679; Mon, 28 Dec 2009 16:37:08 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id 676A08FC20; Mon, 28 Dec 2009 16:37:08 +0000 (UTC) Received: from bigwig.baldwin.cx (66.111.2.69.static.nyinternet.net [66.111.2.69]) by cyrus.watson.org (Postfix) with ESMTPSA id DA9B846B17; Mon, 28 Dec 2009 11:37:07 -0500 (EST) Received: from jhbbsd.localnet (unknown [209.249.190.9]) by bigwig.baldwin.cx (Postfix) with ESMTPA id 39B908A020; Mon, 28 Dec 2009 11:37:07 -0500 (EST) From: John Baldwin To: David Xu Date: Mon, 28 Dec 2009 11:21:30 -0500 User-Agent: KMail/1.12.1 (FreeBSD/7.2-CBSD-20091103; KDE/4.3.1; amd64; ; ) References: <4B317741.8080004@freebsd.org> <200912240759.47703.jhb@freebsd.org> <4B385BB9.3010109@freebsd.org> In-Reply-To: <4B385BB9.3010109@freebsd.org> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Message-Id: <200912281121.30939.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.0.1 (bigwig.baldwin.cx); Mon, 28 Dec 2009 11:37:07 -0500 (EST) X-Virus-Scanned: clamav-milter 0.95.1 at bigwig.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-2.5 required=4.2 tests=AWL,BAYES_00,RDNS_NONE autolearn=no version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on bigwig.baldwin.cx Cc: Daniel Eischen , freebsd-threads@freebsd.org Subject: Re: first patch for process-shared semaphore X-BeenThere: freebsd-threads@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Threading on FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 28 Dec 2009 16:37:08 -0000 On Monday 28 December 2009 2:18:17 am David Xu wrote: > John Baldwin wrote: > > On Wednesday 23 December 2009 10:12:19 pm Alexander Kabaev wrote: > >> On Thu, 24 Dec 2009 09:58:50 +0800 > >> David Xu wrote: > >> > >>> Alexander Kabaev wrote: > >>>> On Thu, 24 Dec 2009 09:22:34 +0800 > >>>> David Xu wrote: > >>>>> libthr does not require semaphore, it implements semaphore, > >>>>> it is easier than other ways to implement the process-shared. > >>>>> > >>>> Let me rephrase: I do not think semaphores belong in libthr. They > >>>> should be either in libc or in librt. > >>>> > >>>> > >>> OK, does others really implement semaphore in librt ? > >>> unfortunately, the librt already requires libpthread to implement > >>> SIGEV_THREAD. > >> I retract that. It appears that there is no consistency - Solaris put > >> these into libc, Linux into libpthread ans SUSv2 hints that these > >> belong with realtime functions. libthr is fine. > > > > I vote for libc. Single-threaded processes can use sem_open() and PSHARED > > sem_init() as well. Single-threaded processes can even use non-PSHARED > > sem_init() by using fork() to create new "threads" that share the semaphore. > > > May I can move all semaphore functions into libc and remove all > semaphore related symbols from libthr ? In pratical, this is not a > problem, because libthr itself is not dlopen-safe, all missing semaphore > functions in libthr will be found in libc by rtld. I would go with this approach. There is also some discussion about moving all of libthr into libc as well and having a dummy libpthread now that we are back to a single threading library and to avoid issues with dlopen() of libpthread, etc. -- John Baldwin