From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <366EDF74.6EE17E0D@jlc.net> Date: Wed, 09 Dec 1998 15:37:08 -0500 From: Dan Malek MIME-Version: 1.0 To: Cort Dougan CC: Troy Benjegerdes , linuxppc-dev@lists.linuxppc.org Subject: Re: PReP RTC vs Decrementer accuracy... References: Content-Type: text/plain; charset=us-ascii Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: Cort Dougan wrote: > Take a look at the decrementer code - I think it's possible to miss a decr > when resetting it. That could explain drift. I finally had a look (after I saw my original message _finally_ got sent to the list :-). We are either going to get it right, or miss a bunch. If the instructions fit in a cache line, I think we are OK because nothing should affect the stream between the get_dec() and set_dec(). If we have to do a cache line fill between these, I think we are hosed........ This is why I used the PIT in my original port of the 8xx stuff. Since the hardware did the reload, there was no timer drift that could be the result of the software (unless you missed one of the imterrupts, which better not happen :-). I went back to the decrementer for the 8xx because it presented an integration hassle....I may now reconsider..... -- Dan [[ This message was sent via the linuxppc-dev mailing list. Replies are ]] [[ not forced back to the list, so be sure to Cc linuxppc-dev if your ]] [[ reply is of general interest. To unsubscribe from linuxppc-dev, send ]] [[ the message 'unsubscribe' to linuxppc-dev-request@lists.linuxppc.org ]]