Date: Sun, 4 Jul 2004 17:20:05 -0400 (EDT) From: Andrew Gallatin <gallatin@cs.duke.edu> To: freebsd-threads@freebsd.org Subject: Re: odd KSE panic Message-ID: <16616.29829.132376.76817@grasshopper.cs.duke.edu> In-Reply-To: <16613.45444.528419.643022@grasshopper.cs.duke.edu> References: <16613.45444.528419.643022@grasshopper.cs.duke.edu>
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Andrew Gallatin writes: > > The problem happens when exiting. When main application thread > decides to exit, it does an ioctl into the driver to wakeup the > sleeping worker thread. The worker thread thread wakes up, and then > exits, then the main thread closes his file descriptor and exits. > > The problem I'm seeing is that I get a panic like the following when > using KSE. (A linux binary works fine, ioctls are translated..) > The problem turned out to be that the worker thread was sleeping in cv_wait_sig() on a cv which was used elsewhere in the driver. When I fixed this, pretty much everything got better. I still don't understand exactly what happened. I have no idea if the worker woke too early, or if the other place this cv was (mis)used was where the early wake happened. (this would be where mx_free() is called). Anyway, it no longer crashes the machine. Sorry to have wasted your time. Now to figure out why libthr does pthread_cond_signal() in my scenario 47us faster than libpthread... (ULE, 1 HTT P4 running SMP kernel) Scenario is that the mainline thread sleeps waiting for a packet (using pthread_cond_timedwait()) and the worker thread is asleep in kernel. When a packet arrives, the worker wakes up, returns from the ioctl, does a pthread_cond_signal() to wakeup the mainline thread, and goes back into the kernel to sleep (via an ioctl). This is the sort of scenario where I thought KSE would be faster than a 1:1 lib.. Drew
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