[ixp1200] Timer from microengines...

[Sprajc, Barry]

>From microcode, there is a cycle_cnt register which returns a 64 bit value
of the cycle count register.  
It's latency is about that of an SDRAM instruction.  It has no interrupt or
signals associated with is, so
your left with polling this register or reading it on a per-packet bases

You could use an SA timer configured to fire off an IRQ at countdown, where
the IRQ handler count send an 
inter_thread signal to one of the microengines.  You could swap out on the
signal, in which case your
microcode sleeps in that thread until the timer is fired off, or you could
use the br_signal instruction 
that causes the microcode for that thead to branch when the inter thread
signal is fired off by the SA, allowing
you to perform other processing until the signal arrvives.

Hope this helps,

barry.sprajc at intel.com



-----Original Message-----
From: Austen McDonald [mailto:austen at cc.gatech.edu]
Sent: Tuesday, June 05, 2001 11:47 AM
To: ixp1200 at CS.Princeton.EDU
Subject: [ixp1200] Timer from microengines...



	Im looking for a timer for use inside microcode (for network
protocol timeout). I know there is the timer from the arm but Ive heard
that the IX bus has some kind of timer that I might be able to tap into?
Does anyone know about this? Must I use the SA timer if I want to wait a
certain period of time?

Austen McDonald
austen at cc.gatech.edu

God does not care about our mathematical difficulties. 
He integrates empirically.
  -- Albert Einstein