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Re: Interrupt latency
- From: David Vrabel <dvrabel at arcom dot com>
- To: ecos-discuss at sources dot redhat dot com
- Date: Thu, 20 Nov 2003 13:02:39 +0000
- Subject: Re: [ECOS] Interrupt latency
- Organization: Arcom Control Systems Ltd
- References: <13907.203.200.40.199.1069331259.squirrel@www.jntu.net>
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.
--
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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