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 [thread overview]
Message-ID: <3ADF609D.8BD4D879@redhat.com> (raw)
In-Reply-To: <KIEBICHBADHFCLGCKOPDEEDOCBAA.jameshq@liv.ac.uk>
[ 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
prev parent reply other threads:[~2001-04-19 15:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-04-19 10:28 Huang Qiang
2001-04-19 15:03 ` Jonathan Larmour [this message]
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