[ECOS] Interrupt Latency

[ECOS] Interrupt Latency

[Indu Mishra]

Hi,
How can we measure the interrupt latency in Ecos. Anybody has some idea 
about it?

regards,

-- 
Indu Mishra



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Re: [ECOS] Interrupt Latency

[Gary Thomas]

Indu Mishra said:
> Hi,
> How can we measure the interrupt latency in Ecos. Anybody has some idea
> about it?

Look at tm_basic.cxx and the support code in kernel/clock.cxx


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Re: [ECOS] Interrupt Latency

[Nick Garnett]

Indu Mishra <mindu@cdotb.ernet.in> writes:

> Hi,
> How can we measure the interrupt latency in Ecos. Anybody has some
> idea about it?

There is code in eCos to measure the latency of timer
interrupts. To measure the latency of other interrupts you probably
need a logic analyzer.

-- 
Nick Garnett                    eCos Kernel Architect
http://www.ecoscentric.com      The eCos and RedBoot experts


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Re: [ECOS] Interrupt latency

[David Vrabel]

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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[ECOS] Interrupt latency

[Giri]

hai,
    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.
    any help is appriciated.
Thanks Regards
Giri

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