Subject: Re: HEADS UP: timecounters (branch simonb-timecounters) merged into
To: Frank Kardel <>
From: Perry E. Metzger <>
List: current-users
Date: 06/09/2006 16:51:29
Frank Kardel <> writes:
>>That's not true. I really would like to be able to use cycle counters
>>for time on my laptop for a number of reasons, including to be able to
>>deal with multimedia applications better and better timestamps for
>>profiling purposes.
> Yes I understand that motivation, but the system can only do a limited
> number of gettimeofday() calls.

Who said anything about system calls -- some of the stuff one wants to
do in the kernel needs to have a good idea of the time.

>>>Given the above limitations and effects a lower frequency counters like
>>>the ACPI timer is just as good for those power saving environments.
>>How good is the ACPI timer?
> Runs at 3579545 Hz - counter ticks in ~279.4 ns

Well, as a fallback, that's at least a lot better than the ancient PC
timer chip. How hard would it be to make that work correctly?

Perry E. Metzger