Tuning the clock Tick Time

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Tuning the clock Tick Time

R Vamshi Krishna

Hello,

I am using a Pentium IV as my target system and since the system is fast
enough, I want to see to how small can I make the "tick" time be and still
manage my applications.

To that end can anyone tell how can I decrease the tick time (say in
micro-seconds range).

Actually we have an application that runs on RTLinux. I want to see if we
can do that in eCos. RTlinux provides very small latencies (micro-seconds
range). Hence I want to check if eCos can also do that.

RTLinux also has a small test that prints all the latencies. Is something
like that available for eCos.

Thanks.

--
Regards,
Vamshi

-------------------------------------------------
R.Vamshi Krishna,
M.Tech. CSE (II year),
IIT Bombay
Room no. 320, A-wing, Hostel-12
Mobile : +919869781633
-------------------------------------------------

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Re: Tuning the clock Tick Time

Gary Thomas
On Tue, 2005-12-20 at 01:12 +0530, R Vamshi Krishna wrote:

> Hello,
>
> I am using a Pentium IV as my target system and since the system is fast
> enough, I want to see to how small can I make the "tick" time be and still
> manage my applications.
>
> To that end can anyone tell how can I decrease the tick time (say in
> micro-seconds range).
>
> Actually we have an application that runs on RTLinux. I want to see if we
> can do that in eCos. RTlinux provides very small latencies (micro-seconds
> range). Hence I want to check if eCos can also do that.

eCos can definitely provide micro-second event latencies.  This is not
related to how fast the clock runs though - a well designed system does
not rely on a clock/timer to make things happen.

>
> RTLinux also has a small test that prints all the latencies. Is something
> like that available for eCos.

Look at CYGVAR_KERNEL_COUNTERS_CLOCK_LATENCY and CYGVAR_KERNEL_COUNTERS_CLOCK_DSR_LATENCY
in the kernel package.  These can be enabled and the 'tm_basic' program
will use them, providing a simple measure of clock/timer ISR and DSR
latencies.

--
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------


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Re: Tuning the clock Tick Time

R Vamshi Krishna

I think it was my mistake because I did not properly phrase my question.
In RTLinux not only latencies but also periodicity of threads can also be
given in terms of Micro-Seconds.

So in eCos when I correspondigly write alarms, I want to be able to set
alarms of micro-seconds range.

Is it possible ??

If Context switches are indeed in micro-seconds range, and default
tick-time is 100 per second, then how can I find out the exact time for
context switch in eCos ?

On Mon, 19 Dec 2005, Gary Thomas wrote:

> On Tue, 2005-12-20 at 01:12 +0530, R Vamshi Krishna wrote:
>> Hello,
>>
>> I am using a Pentium IV as my target system and since the system is fast
>> enough, I want to see to how small can I make the "tick" time be and still
>> manage my applications.
>>
>> To that end can anyone tell how can I decrease the tick time (say in
>> micro-seconds range).
>>
>> Actually we have an application that runs on RTLinux. I want to see if we
>> can do that in eCos. RTlinux provides very small latencies (micro-seconds
>> range). Hence I want to check if eCos can also do that.
>
> eCos can definitely provide micro-second event latencies.  This is not
> related to how fast the clock runs though - a well designed system does
> not rely on a clock/timer to make things happen.
>
>>
>> RTLinux also has a small test that prints all the latencies. Is something
>> like that available for eCos.
>
> Look at CYGVAR_KERNEL_COUNTERS_CLOCK_LATENCY and CYGVAR_KERNEL_COUNTERS_CLOCK_DSR_LATENCY
> in the kernel package.  These can be enabled and the 'tm_basic' program
> will use them, providing a simple measure of clock/timer ISR and DSR
> latencies.
>
>

--
Regards,
Vamshi

-------------------------------------------------
R.Vamshi Krishna,
M.Tech. CSE (II year),
IIT Bombay
Room no. 320, A-wing, Hostel-12
Mobile : +919869781633
-------------------------------------------------

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Fwd: [ECOS] Tuning the clock Tick Time

Fabian Scheler
Hi,

> If Context switches are indeed in micro-seconds range, and default
> tick-time is 100 per second, then how can I find out the exact time for
> context switch in eCos ?
>

by using the 'rdtsc' instruction of the pentium IV.

Ciao, Fabian

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