On Tue, Feb 20, 2007 at 07:41:25PM +0300, Evgeniy Polyakov wrote: > It can be recvfrom only problem - syscall overhead on my p4 (core duo, > debian testing) is bout 300 usec - to test I ran read('dev/zero', &data, > 0) in a loop.
nsec I assume? The usec numbers for read(fd, &c, 0) where fd is /dev/zero: 1.557667, 0.627667, 0.447333, 0.440000, 0.440000, 0.440000, 0.442333, 0.440000, 0.440000, 0.442333, 0.442333, 0.440000, 0.440000, 0.442333, 0.442667, 0.440000, 0.440000, 0.440000, 0.442333, 0.442667, In usecs. Notice the same declining figure, but not as pronounced. With a sleep(1) in between, we get: 1.692667, 1.800000, 0.782667, 1.282667, 0.665000, 0.980000, 0.925000, 0.887667, 0.662667, 0.862667, 1.077333, 1.442333, 0.660000, 1.890000, 0.672333, 0.795000, 0.647667, 0.692333, 0.750000, 0.865000, This doesn't look all that unhealthy. > Could you try to hack recvfrom() for your socket to always copy some > empty buffer and check the results without waiting for packet? That might be out of my reach before tomorrow :-) > If you are not hurry I can test it myself tomorrow. Thanks. My major problem is that in my measurements, I quite often see the 'worst case' 4usec result. It would not be a problem if it happens only once, of course. Bert -- http://www.PowerDNS.com Open source, database driven DNS Software http://netherlabs.nl Open and Closed source services - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html