Re: [Discuss-gnuradio] GNU Radio CVS-current vmcirbuf problems

[Eric Blossom]

On Thu, Oct 13, 2005 at 06:32:03AM +0930, Berndt Josef Wulf wrote:
> >
> > (1) Re sysv_shm, increase the system limits using sysctl:
> >
> >   http://mail-index.netbsd.org/tech-kern/2002/07/07/0003.html
> 
> shminfo:
>         shmmax: 268435456       (max shared memory segment size)
>         shmmin:       1 (min shared memory segment size)
>         shmmni:     128 (max number of shared memory identifiers)
>         shmseg:     128 (max shared memory segments per process)
>         shmall:   65536 (max amount of shared memory in pages)
> 


Try increasing shmmni and shmseg to 512 or 1024.

> > (2) gr_vmcircbuf_mmap_shm_open might work.
> >
> > It requires mmap and shm_open.  mmap has been around forever, and
> > shm_open is defined in POSIX 1003.1 (2001).  Does NetBSD implement
> > both of these calls?  If so, our configure tests need some tweaking.
> > Can you confirm or deny the availability of shm_open on NetBSD, and if
> > it exits, which library it's contained in?
> 
> mmap(2) as part of libc, but I couldn't find shm_open(?) in the hurry but the 
> following:
> 
> shmat, shmdt (2) - map/unmap shared memory
> shmctl (2) - shared memory control operations
> shmget (2) - get shared memory segment

These are the SysV shared memory system calls.  

> 
> > (3) Fix gr_vmcircbuf_mmap_tmpfile so that it works reliably, and doesn't
> > unmap pieces of the address space that it didn't map in.
> >
> > (4) Come up with some other way to get a single piece of physical
> > memory mapped into two adjacent virtual addresses.  You may be able to
> > use mmap with MAP_ANON and/or /dev/zero and then remap it using some
> > kind of /proc/self/mem trick (didn't work on GNU/Linux).
> 
> Just when I thought things have settled ready for the next release... ;-)

Sorry about that!  
I suspect that increasing shmmni and shmseg will fix your problem.

> Anyone with FreeBSD seeing this problem too?
> 
> cheerio Berndt

Eric