From: Steven Scholz <steven.scholz@imc-berlin•de>
To: linuxppc-embedded@ozlabs•org
Subject: Re: MPC8xx: resolution of gettimeofday() ?
Date: Mon, 22 May 2006 13:03:50 +0200 [thread overview]
Message-ID: <44719A96.2020309@imc-berlin.de> (raw)
In-Reply-To: <20060519175513.GA12121@gate.ebshome.net>
Eugene,
>>> Usually on PPC we use timebase to interpolate time between Decrementer
>>> interrupts. In this case gettimeofday resolution is determined by
>>> timebase resolution which is quite high (megahertz range).
>> Sorry. I don't understand. What do you mean with "timebase"? Is there a
>> second timer/counter?
>
> PowerPC has a facility called timebase. This is 64-bit counter which
> can be accessed using special instructions (mftb, mftbu on 32-bit PPC).
> Counter resolution depends on particular chip implementation, some
> use core clock, other use bus clock...
>
> It's similar to the time-stamp counter in Intel CPUs (accessed
> with rdtsc instruction).
Thanks very much for clearing this!
> Please, refer to PPC arch manuals for more information. Also, if you
> really interested in how gettimeofday() is implemented, why don't you
> look at the source code yourself?
I tried. But it's not obvious. Not for me anyway.
--
Steven
prev parent reply other threads:[~2006-05-22 11:03 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-18 15:10 MPC8xx: resolution of gettimeofday() ? Steven Scholz
2006-05-18 16:48 ` Eugene Surovegin
2006-05-19 8:08 ` Steven Scholz
2006-05-19 17:55 ` Eugene Surovegin
2006-05-22 11:03 ` Steven Scholz [this message]
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