Re: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4]

[Ingo Molnar]

* Florian Schmidt <mista.tapas@xxxxxxx> wrote:

> > > fs.h chunk went missing ... uploading -V0.5.14 in a minute.
> > 
> > done.
> 
> compiles and boots fine. no observable change in xrun behaviour
> though. 

do you compile jackd from sources? If yes then could you try the patch
below? With this added, the kernel will produce a stackdump whenever
jackd does an 'illegal' sleep.

Also, could you do a small modification to kernel/sched.c and remove
this line:

		send_sig(SIGUSR1, current, 1);

just to make it easier to get Jack up and running. (by default an
atomicity violation triggers a signal to make it easier to debug it in
userspace, but i suspect there will be alot of such violations so jackd
would stop all the time.)

	Ingo

--- jack-audio-connection-kit-0.99.0/drivers/alsa/alsa_driver.c.orig
+++ jack-audio-connection-kit-0.99.0/drivers/alsa/alsa_driver.c
@@ -1161,6 +1161,7 @@ alsa_driver_wait (alsa_driver_t *driver,
 		unsigned int p_timed_out, c_timed_out;
 		unsigned int ci = 0;
 		unsigned int nfds;
+		int ret;
 
 		nfds = 0;
 
@@ -1194,7 +1195,11 @@ alsa_driver_wait (alsa_driver_t *driver,
 
 		poll_enter = jack_get_microseconds ();
 
-		if (poll (driver->pfd, nfds, driver->poll_timeout) < 0) {
+		gettimeofday((void *)1,(void *)0); // atomic off
+		ret = poll (driver->pfd, nfds, driver->poll_timeout);
+		gettimeofday((void *)1,(void *)1); // atomic on
+
+		if (ret < 0) {
 
 			if (errno == EINTR) {
 				printf ("poll interrupt\n");
-
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