From owner-freebsd-threads@FreeBSD.ORG Thu Apr 10 09:20:50 2003 Return-Path: Delivered-To: freebsd-threads@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 90D0937B401 for ; Thu, 10 Apr 2003 09:20:50 -0700 (PDT) Received: from fledge.watson.org (fledge.watson.org [204.156.12.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id ECCA143FB1 for ; Thu, 10 Apr 2003 09:20:49 -0700 (PDT) (envelope-from robert@fledge.watson.org) Received: from fledge.watson.org (fledge.pr.watson.org [192.0.2.3]) by fledge.watson.org (8.12.9/8.12.9) with SMTP id h3AGL8YY039750; Thu, 10 Apr 2003 12:21:09 -0400 (EDT) (envelope-from robert@fledge.watson.org) Date: Thu, 10 Apr 2003 12:21:07 -0400 (EDT) From: Robert Watson X-Sender: robert@fledge.watson.org To: Craig Rodrigues In-Reply-To: <20030410050835.GA37060@attbi.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: freebsd-threads@freebsd.org Subject: Re: Scope system threads (was Re: PS_BLOCKED) X-BeenThere: freebsd-threads@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Threading on FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Apr 2003 16:20:50 -0000 On Thu, 10 Apr 2003, Craig Rodrigues wrote: > FreeBSD lacks POSIX real-time signals, which was very troublesome when I > was trying to get the ACE Proactor to work properly, because the > Proactor uses POSIX AIO + POSIX RT signals. I would really like to see > POSIX RT signals on FreeBSD. There was some earlier work done by Juli Mallett to introduce reliable signals, which supported some of the elements of the POSIX realtime signal requirements. However, there were a fair number of implementation details that hadn't been addressed at that point that really needed to be addressed before the changes could be merged (largely related to reliability and stability concerns). I'd be interested in seeing that work brought back to life, perhaps on a Perforce branch. One of the concerns with the reliable signalling bits was that it required more kernel memory allocation, often while holding locks -- I suspect things can be reworked to avoid that burden without too much difficulty. Interestingly, it looked like on some other operating systems the introduction of reliable signaling actually resulted in the potential loss of signals in low memory scenarios :-). Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Network Associates Laboratories