On Fri, Jan 23, 2009 at 01:01:24PM -0500, Marcus D. Leech wrote: > I can't use FFTs larger than about 180000 bins without getting "shared > memory allocation" errors in Gnu Radio. > > Is there an easy fix for this? > > For SETI work, being able to (for example) compute an 8 million point > FFT for an 8Msps signal gives you 1Hz > resolution. But I can't seem to get anywhere near this without the > allocator griping at me. >
Hi Marcus, You need to bump up the shared memory maximum segment size. You can do this with the sysctl command. On some systems there's also an /etc/sysctl.conf file. The defaults appear to depend on your distribution. The parameter you want to increase is kernel.shmmax. [...@cyan trunk]$ sudo sysctl -a | grep shm kernel.shmmax = 268435456 kernel.shmall = 2097152 kernel.shmmni = 4096 vm.hugetlb_shm_group = 0 The output above is from an x86 Fedora 9 system. It's pretty big by default. See also $ man sysctl $ man sysctl.conf http://bugzilla.kernel.org/show_bug.cgi?id=11381 Eric _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio