On Sun, Feb 25, 2007 at 11:41:54AM +0100, Pavel Machek ([EMAIL PROTECTED]) wrote: > > > I've done so, with some interesting results. Source on > > > http://ds9a.nl/tmp/recvtimings.c - be careful to adjust the '3000' divider > > > to your CPU frequency if you care about absolute numbers! > > > > > > These are two groups, each consisting of 10 consecutive nonblocking UDP > > > recvfroms, with 10 packets preloaded. Reported is the number of > > > microseconds > > > per recvfrom call which yielded a packet: > > > > > > $ ./recvtimings > > > 4.142333 > > > > It can be recvfrom only problem - syscall overhead on my p4 (core duo, > > debian testing) is bout 300 usec - to test I ran > > core duo is _not_ p4 class cpu; rsulets there will be very different.
Results nevertheless are the same. Each syscall takes some time first (noticebly more than subsequent calls), and that was a main problem for Bert. Given the high load, recvfrom() can even take tens of microseconds (although I can not provide a profile output yet, but I showed a data). So, syscall overhead itself is very small no matter which type of the CPU is used - athlon is about 300 nsec, via epia about 1.4 usec), but the whole function can take quite a lot of time. > Pavel > > -- > (english) http://www.livejournal.com/~pavelmachek > (cesky, pictures) > http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- Evgeniy Polyakov - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
