This is just an educated guess, so anyone, please correct me if I am wrong:
GR tries to hide the fact that even for a ringbuffer, memory space is always linear. Now lets assume you try to do an fft with overlap, with an fft size as large as your buffer. The first time, you memory area might be at the beginning of the buffer. The next time, it is shifted somewhat into the buffer, therefor the last part of your buffer is actually at the beginning of the buffer. To get a linear (with monotonically increasing adresses) buffer, the physical memory pages backing your buffer are mapped into virtual memory space twice, where the second mapping directly follows the first. Physical memory usage is equal to buffer size, whereas virtual memory space uses twice as much memory. So for current applications on todays computer it is really easy to run out of virtual memory space. If your demands are really so high, why aren't you using a 64bit machine. On top of the larger memory space, you get more registers and guranteed existence of SSE (only an issue, if you use prebuilt packages). The last time I used GR, it worked fine on 64bit. Stefan _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
