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* [ECOS] Is clock interrupt = tick ?
@ 2001-04-19 10:28 Huang Qiang
  2001-04-19 15:03 ` Jonathan Larmour
  0 siblings, 1 reply; 2+ messages in thread
From: Huang Qiang @ 2001-04-19 10:28 UTC (permalink / raw)
  To: eCos



^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [ECOS] Is clock interrupt = tick ?
  2001-04-19 10:28 [ECOS] Is clock interrupt = tick ? Huang Qiang
@ 2001-04-19 15:03 ` Jonathan Larmour
  0 siblings, 0 replies; 2+ messages in thread
From: Jonathan Larmour @ 2001-04-19 15:03 UTC (permalink / raw)
  To: Huang Qiang; +Cc: eCos

[ 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

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