From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jonathan Larmour <jlarmour@redhat.com>
To: Huang Qiang <jameshq@liverpool.ac.uk>
Cc: eCos <ecos-discuss@sources.redhat.com>
Subject: Re: [ECOS] Is clock interrupt = tick ?
Date: Thu, 19 Apr 2001 15:03:00 -0000
Message-id: <3ADF609D.8BD4D879@redhat.com>
References: <KIEBICHBADHFCLGCKOPDEEDOCBAA.jameshq@liv.ac.uk>
X-SW-Source: 2001-04/msg00232.html

[ Is clock interrupt = tick? ]

It may depend on your terminology. Most hardware clocks have an internal
counter, often a resetting decrementer which you program to trigger an
interrupt when it hits zero.

It's up to you whether you consider the change in the value of the
decrementer to be a tick, or the clock interrupt to be a tick. My
preference is for the latter, and I think that is definitely the most
common usage. So in short, yes :-).

But note that kernel timeslicing doesn't take place every clock interrupt -
it actually happens according to the eCos CDL option 
CYGNUM_KERNEL_SCHED_TIMESLICE_TICKS, which defaults to 5 ticks between
reschedules.

Jifl