From: Jan Kiszka <jan.kiszka@domain.hid>
Cc: manoj kumar <manojkpanghal@domain.hid>, xenomai@xenomai.org
Subject: Re: [Xenomai-core] getting negative values in interrupt latency in xenomai
Date: Wed, 23 May 2007 10:07:18 +0200 [thread overview]
Message-ID: <4653F636.1090700@domain.hid> (raw)
In-Reply-To: <305035a40705230025q50e05401xa76dbb966a24c254@domain.hid>
Gregory CLEMENT wrote:
> 2007/5/23, manoj kumar <manojkpanghal@domain.hid>:
>> Hi,
>>
>> i am runnigthe latency test on i386 platform with 1 GB ram and intel pentium
>> 4 runnig at 2.66GHz . i am getting some negative values as lat best and avg.
>> The results are as below
>>
>>
>> User space interrupt latency output
>>
>> == Sampling period: 10000 us
>>
>> == Test mode: periodic user-mode task
>>
>> == All results in microseconds
>>
>> warming up...
>>
>> RTT| 00:00:01 (periodic user-mode task, 10000 us period, priority 99)
>>
>> RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat
>> worst
>>
>> RTD| -1.775| -1.374| 0.953| 0| -1.775|
>> 0.953
>>
>> RTD| -1.790| -1.355| 3.142| 0| -1.790|
>> 3.142
>>
>> RTD| -1.812| -1.266| 4.158| 0| -1.812|
>> 4.158
>>
>> RTD| -1.797| -1.272| 6.602| 0| -1.812|
>> 6.602
>>
>> RTD| -1.764| -1.365| 0.575| 0| -1.812|
>> 6.602
>>
>> RTD| -1.895| -1.370| 0.859| 0| -1.895|
>> 6.602
>>
>> RTD| -1.857| -1.421| 0.908| 0| -1.895|
>> 6.602
>>
>> RTD| -1.782| -1.293| 5.845| 0| -1.895|
>> 6.602
>>
>> RTD| -1.929| -1.362| 1.204| 0| -1.929|
>> 6.602
>>
>> RTD| -1.775| -1.359| 0.844| 0| -1.929|
>> 6.602
>>
>> RTD| -1.794| -1.346| 0.724| 0| -1.929|
>> 6.602
>>
>> RTD| -1.756| -1.318| 1.021| 0| -1.929|
>> 6.602
>>
>> RTD| -1.775| -1.269| 8.064| 0| -1.929|
>> 8.064
>>
>> RTD| -1.805| -1.395| 0.893| 0| -1.929|
>> 8.064
>>
>> RTD| -1.779| 1.530| 281.147| 0| -1.929|
>> 281.147
>>
>> RTD| -1.959| -1.362| 1.118| 0| -1.959|
>> 281.147
>> Could any figure out why these negative values are coming and reason behind
>> that and how i can avoid these.
>>
>> is it a configuration issuse.
>
> You have to calibrate xenomai by feeding with your average latency
> /proc/xenomai/latency
>
...or by setting it at compile time in the kernel .config.
Anyway, I would worry more about that +280 us latency. Probably
SMI-related. Please check TROUBLESHOOTING regarding potential reasons
and solutions.
Jan
prev parent reply other threads:[~2007-05-23 8:07 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-23 6:10 [Xenomai-core] getting negative values in interrupt latency in xenomai manoj kumar
2007-05-23 7:25 ` Gregory CLEMENT
2007-05-23 8:07 ` Jan Kiszka [this message]
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