From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dirk Roloff <roloff@domain.hid>
Subject: Re: [Adeos-main] 260 uSec latency and no idea why
Date: Fri, 12 Mar 2004 04:22:44 +0100
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Am Donnerstag, 11. M=E4rz 2004 20:04 schrieb Paolo Mantegazza:

Hi Paolo,

> Dirk Roloff wrote:
> Have you tried using rt_get_cpu_time_ns to avoid mixing up with Linux
> stuff?=20


No i don't because i am not using rtai. I "just" use an adeos patched kerne=
l.
But i changed the do_gettimeofday() by a rdtsc call. I dont want to know th=
e time,
just the time elapsed. So i dont need the time calculation done by do_getti=
meofday()
and i avoid mixing stuff. But the results are the same. :-(

>Have you checkd the interrupt level acknolwdge jitter/latency using
> the calibration tool available in RTAI?

again - no rtai

> Can you change your code so that it can be used anywhere? In such a case
> it would be simple to run it on a safe machine (e.g. mine) and see if it
> can be repeated, or is machine specific (yours).

Yes but it will not help a lot. I can't see such a latency on other machine=
s.
f.e. on my Box here at home 7-17 MicroSec in the adeos domain.
And i try stressing the Box- but its a complete different h/ware.

So it must be the celeron box or some kernel/compiler settings on it.

But what is able to delay the delivery of an interrupt if there is no one=20
calling cli or masking irq's (Both is prohibited by adeos isn't it ?)

One thing would be waking a suspended cpu - but i disabled APM.
Someone told me Intel SpeedStep switching the mode will take hundrets of Mi=
croSecs
but i didn't find what this is yet. Have to google some more.

Dirk.