From owner-freebsd-chat Thu Oct 26 18:46:57 2000 Delivered-To: freebsd-chat@freebsd.org Received: from fw.wintelcom.net (ns1.wintelcom.net [209.1.153.20]) by hub.freebsd.org (Postfix) with ESMTP id C10CA37B479 for ; Thu, 26 Oct 2000 18:46:55 -0700 (PDT) Received: (from bright@localhost) by fw.wintelcom.net (8.10.0/8.10.0) id e9R1knD11185; Thu, 26 Oct 2000 18:46:49 -0700 (PDT) Date: Thu, 26 Oct 2000 18:46:49 -0700 From: Alfred Perlstein To: Alan Cox Cc: Jonathan Lemon , Gideon Glass , Simon Kirby , Dan Kegel , chat@FreeBSD.ORG, linux-kernel@vger.kernel.org Subject: Re: kqueue microbenchmark results Message-ID: <20001026184649.U28123@fw.wintelcom.net> References: <20001026201042.A38500@prism.flugsvamp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.4i In-Reply-To: ; from alan@lxorguk.ukuu.org.uk on Fri, Oct 27, 2000 at 02:32:59AM +0100 Sender: owner-freebsd-chat@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org * Alan Cox [001026 18:33] wrote: > > the application of a close event. What can I say, "the fd formerly known > > as X" is now gone? It would be incorrect to say that "fd X was closed", > > since X no longer refers to anything, and the application may have reused > > that fd for another file. > > Which is precisely why you need to know where in the chain of events this > happened. Otherwise if I see > > 'read on fd 5' > 'read on fd 5' > > How do I know which read is for which fd in the multithreaded case No you don't, you don't see anything with the current code unless fd 5 is still around, what you're presenting to Jonathan is a application threading problem, not something that need to be resolved by the OS. > > As for the multi-thread case, this would be a bug; if one thread closes > > the descriptor, the other thread is going to get an EBADF when it goes > > to perform the read. > > Another thread may already have reused the fd This is another example of an application threading problem. -- -Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org] "I have the heart of a child; I keep it in a jar on my desk." To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message