On Monday, August 02, 2010 6:13:50 pm Guy Helmer wrote: > On a FreeBSD 7.1 SCHED_ULE kernel, I have a large number of files opened and > mmapped (with MAP_NOSYNC option) for shared-memory communication between > processes. Normally, memcpy() copies data into these shared-memory buffers > in a reasonable amount of time closely related to the size of the copy > (roughly 10us per 10KB). However, due to performance issues I've found that > sometimes a memcpy() takes an abnormally long time (10ms for 40KB, and I > suspect longer times occurring when I have not had monitoring enabled). The > system doesn't seem to be in memory overcommit -- there is just a minor > amount of swap in use, and I've not seen page-ins or page-outs while > watching systat or vmstat. > > Since I'm using MAP_NOSYNC, I would not expect the pager to flush dirty > pages to disk and cause add delays. Any ideas where to look? Might it help > to pin threads to CPUs in case a thread is getting moved to a different > core?
Pinning might help yes. You might also want to ensure there aren't any interrupts on that CPU. Currently there isn't a good way to figure that out short of kgdb though. :( -- John Baldwin _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
