From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [PATCH] Use pipe() to simulate signalfd() (v2) Date: Sun, 04 May 2008 09:46:11 -0500 Message-ID: <481DCC33.50707@codemonkey.ws> References: <1209757346-15076-1-git-send-email-aliguori@us.ibm.com> <481D7C88.1080609@qumranet.com> <481DC662.7010501@codemonkey.ws> <481DCAA5.3090807@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel@lists.sourceforge.net, Marcelo Tosatti To: Avi Kivity Return-path: In-Reply-To: <481DCAA5.3090807@qumranet.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces@lists.sourceforge.net Errors-To: kvm-devel-bounces@lists.sourceforge.net List-Id: kvm.vger.kernel.org Avi Kivity wrote: > Anthony Liguori wrote: >>> We can keep the signals blocked, but run the signalfd emulation in a >>> separate thread (where it can dequeue signals using sigwait as an >>> added bonus). This will reduce the differences between the two >>> modes at the expense of increased signalfd() emulation complexity, >>> which I think is a good tradeoff. >>> >> >> signalfd() can't be emulated transparently with a separate thread >> because you won't be able to wait on signals destined for the >> specific thread (only signals sent to the process). We deliver >> signals directly to the IO thread (specifically, SIGUSR1) so this >> could get nasty. We could just not block SIGUSR1 and rely on the >> fact that it will break us out of select() but I that makes things a >> bit more subtle than I'd like. >> > > We can completely kill off SIGUSR1 and replace it with its own pipe. > There's hardly any point in asking the kernel to signal a task, then > having the kernel convert this to a fd write. > > (Or maybe use eventfd()) That's a really good idea. I'll update the patch. Regards, Anthony Liguori ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone