Christophe Vescovi <vescovi@xxxxxxxxxxxxx> writes: > Well in fact I use jack with POSIX shm for a few month now and every > thing is fine. I can run all jack audio app I have without any > problem with my cheap SBLive. I have no xrun with -p1024 and a few > when switching desktop or starting apps with -p512 (which seems to > be the normal behaviour with a SBLive). > > But it seems that there is a preference for SysV shm (this is the > default in configure !!) so I was wondering why. I sometimes run POSIX shm on my Linux system for testing purposes to make sure it continues working. As far as I can tell, it works fine. The MacOSX port uses POSIX shm exclusively. An earlier POSIX shm implementation worked, but not reliably. This was blamed at the time on bugs in the Linux kernel. I have not observed these problems on my system, but they were the reason why Paul decided to make System V shm the default on Linux. There were also install problems due to the requirement that users create an /etc/fstab entry of type tmpfs for /dev/shm. It may be that newer kernels have a more robust POSIX shm support. Or, perhaps the present JACK shm implementation not longer stresses whatever component was failing before. Or, maybe I just haven't run it enough to notice, yet. :-) The problems that you mention are serious and should be reported in the JACK bug database, <http://jackit.sourceforge.net/mantis>. -- joq
