This should not be changed in the *standard* kernel but should be
available as a socket option so that people who build clusters using
switched Fast Ethernet can get reasonably responsive TCP. We do this by
changing the default "HZ/5" to the more responsive "HZ/50" whenever
TCP_NODELAY socket option is set.
BTW, there are other timeout values which can and should be changed for
clusters using TCP_NODELAY sockets (e.g. the full second retransmit
timer when sh->users is set and another seldom used 30 second partial
packet timer).
These issues are of crucial importance for Linux based clusters, which
use TCP in ways very different from "standard". Improving a few timeout
constants is a start, but in the future, we'll probably see more
elaborate TCP enhancements driven by the needs of parallel processing
applications.
Sincerely,
Josip
-- Dr. Josip Loncaric, Senior Staff Scientist mailto:josip@icase.edu ICASE, Mail Stop 132C http://www.icase.edu/~josip/ NASA Langley Research Center mailto:j.loncaric@larc.nasa.gov Hampton, VA 23681-2199, USA Tel. +1 757 864-2192 Fax +1 757 864-6134- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/