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Re: clarification need for "tm_baic" test case
- From: "Gary D. Thomas" <gary dot thomas at mind dot be>
- To: radhakrishnan R <radhaamanji at yahoo dot co dot uk>
- Cc: eCos Discussion <ecos-discuss at sources dot redhat dot com>
- Date: 22 May 2003 09:13:47 -0600
- Subject: Re: [ECOS] clarification need for "tm_baic" test case
- Organization:
- References: <20030522045154.45633.qmail@web14308.mail.yahoo.com>
On Wed, 2003-05-21 at 22:51, radhakrishnan R wrote:
> Hello,
> Iam trying to run the "tm_basic" test case
> available in eCos "kernel" package for my target.
>
> problem summary:
> "
> During the kernel primitives timing measurement,
> if the timer interrupt occurs, the timing for ISR is
> also taken in to account. Is this is expected
> implementation or the ISR timer need to be excluded in
> measurement?.
>
> To measure the timing for the kernel primitives a
> the ticks maintained in timer counter is used.
> The timer counter works like this.
> "The timer is programmed to interrupt the
> Processor every 1 milli second. The timer is
> initialized to count and increment every 1 Micro
> second.
> So every 1 microsecond my timer counter will
> increment and when it reaches 1 milisecond it will
> interrupt the Processor."
> The question is "when the timer interrupt occurs
> because it has reached the limit, the timer ISR is
> executed". Because of the ISR execution the time taken
> for the ISR is also included in the Kernel primitives
> timing measurement. Is the time taken to execute ISR
> also be included in measurement??.
>
What actually gets measured is the latency - the time from
the interrupt occurring until the ISR routine actually runs.
Look at the code - the measurement happens early in the ISR.
There is no measurement of the ISR per-se, but there can be
an additional measurement of the ISR -> DSR latency.
Again, the code is all out there for you to read.
kernel/current/src/common/clock.cxx
--
Gary D. Thomas <gary.thomas@mind.be>
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