On Tuesday 15 March 2011 03:51 pm, John Baldwin wrote: > On Tuesday, March 15, 2011 3:26:11 pm Jung-uk Kim wrote: > > Now don't you think we should really kill delay by TSC? ;-) > > Delay by TSC fixed known deadlocks with the i8254 based DELAY() due > to the use of locks. Be careful that you don't re-introduce old > bugs.
Yeah, that's perfectly understood. > Also, you can use a TSC for DELAY() in cases when it is not safe to > use it for the timecounter (if it is not in sync across cores, but > is used in a machine with invariant TSCs or where the user knows > they won't ever throttle it). Modern Intel CPUs all have invariant > TSCs that are more or less in sync across cores, and we should > certainly still use the TSC for DELAY() in that case. Even if they > aren't in sync (so we can't use it for the timecounter) we should > still use the TSC if they are invariant as it is far cheaper than > anything else. That, too, is well understood. You know I added tsc_is_invariant myself. :-) However, why do we need cheaper DELAY() when we trying to "delay" something with it? Jung-uk Kim _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
