Re: dtrace users opinion solicited (timestamps)


On Fri, 10 Jul 2009, Andriy Gapon wrote:

Thinking aloud - maybe we could always use one value of tsc_freq (or something like max_tsc_freq). This wouldn't give us correct timestamps when TSC frequency is changing, but it would give us something that is always proportional to TSC value and thus has its properties - monotonicity in the first place. And, of course, there is no problem when TSC frequency is constant.

Just a point from a user perspective: I find it useful (important even) to be able to compare timing between runs on the same box, and while that means I need to control for the frequency changing in an experimental sense, in as much as timestamp measurements in dtrace can be normalized, that would be helpful.

Robert N M Watson
Computer Laboratory
University of Cambridge
_______________________________________________
freebsd-current@xxxxxxxxxxx mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-current
To unsubscribe, send any mail to "freebsd-current-unsubscribe@xxxxxxxxxxx"