[ECOS] Interrupt latency
David Vrabel
dvrabel@arcom.com
Thu Nov 20 13:02:00 GMT 2003
Hi,
> i am using i386 PC based platform. and UART is 16c550 with FIFO is
> disabled.i am not able to find out the interrupt latency for each
> charecter that i received. could u please send me the rough figures if
> any body calculated or having rough idea of how much it will be.
You'll need to measure it yourself as it's very system dependant. I've
used a 'scope for this in the past.
For example, with a 25MHz i386EX doing nothing extra but timer
interrupts and a trivial external interrupt whose handler does nothing
but toggle a GPIO line I got the following results:
Typical Maximum[*]
ISR latency/us 22 74
DSR latency/us 108 90
Throw in some ethernet traffic...
Typical Maximum[*]
ISR latency/us 24 92
DSR latency/us 110 544
David Vrabel
[*] Maximum in about 1.2 million samples.
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David Vrabel, Design Engineer
Arcom, Clifton Road Tel: +44 (0)1223 411200 ext. 3233
Cambridge CB1 7EA, UK Web: http://www.arcom.com/
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