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Re: Question about Instrumentation? Thanks
- From: Nick Garnett <nickg at ecoscentric dot com>
- To: "Qiang Huang" <jameshq at liverpool dot ac dot uk>
- Cc: "Ecos-Discuss" <ecos-discuss at sources dot redhat dot com>
- Date: 26 Mar 2003 11:18:49 +0000
- Subject: Re: [ECOS] Question about Instrumentation? Thanks
- References: <BDEPKKELILOKGOAOMONOIEEGCCAA.jameshq@liv.ac.uk>
"Qiang Huang" <jameshq at liverpool dot ac dot uk> writes:
> Hi all:
> I just tried to use kernel instrumentation in ecos. I have a question:
> Seen from the source code in "instrmnt/meminst.cxx", In function
> "cyg_instrument( )" it just record the time stamp by reading the clock as
> "HAL_CLOCK_READ( &p->timestamp );", but the system clock is running forever
> and roll over when it reach the limits, so through the whole program the
> clock may have already been roll over some times so how can I interept the
> time stamp recorded by the kernel instrumentation? probably a later
> instrumentation will have the time stamp less than the earlier one? so how?
> Am I wrong somewhere?
>
The idea is that if timing over long periods is required, then you
should use the instrumentation entries stored by the clock DSR to
calculate correct timestamps.
--
Nick Garnett eCos Kernel Architect
http://www.ecoscentric.com/ The eCos and RedBoot experts
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