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Re: Meeting minutes 20060727
Hi Jose,
Jose R. Santos wrote:
> Actually, in the email that was directed at Masami-san I stated two
> scenarios that prevent us just using get_cycles(). One is processors
> that support frequency scaling and the second one is virtulized
> environments like Xen or Power5 micro partitions. This was something
> that Masami-san and myself were discussing at OLS, as one of his main
> concerns with LKET the performance impact of do_gettimeofday() as a
> timestamp mechanism. The things that I wrote on my email to Masami-san
> were a continuation of those discussion we had at OLS in an effort to
> standardize the tracing mechanism.
I think we can use get_cycles() even if the processor's frequency can be
changed, because we can re-calculate time by using the events which
records frequency changing. However, in the case of Xen, it would be more
difficult to record these kinds of events.
Thanks,
--
Masami HIRAMATSU
2nd Research Dept.
Hitachi, Ltd., Systems Development Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com