From: Jan Kiszka <jan.kiszka@domain.hid>
To: Rudolf Marek <rudolf.marek@domain.hid>
Cc: xenomai@xenomai.org
Subject: Re: [Xenomai-help] negative values of latency/klatency
Date: Tue, 28 Feb 2006 13:33:00 +0100 [thread overview]
Message-ID: <440442FC.8090100@domain.hid> (raw)
In-Reply-To: <440324EE.6030309@domain.hid>
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Rudolf Marek wrote:
> Hello all,
>
> I tried the latency and klatency demo on some PPC procesor(s) (e500 and 60x) and the measurement results are rather strange.
> I observed this with arbitrary version of Adeos/ipipe and on Xenomai 2.0.3 older 2.0.x too.
>
> -sh-3.00# ./run -- -T 10 -h -l 5
> ...
> RTT| 00:00:01
> RTH|----klat min|----klat avg|----klat max| overrun|---klat best|--klat worst
> RTD| -4525| -4323| 5777| 0| -4525| 5777
> RTD| -4525| -4444| -1777| 0| -4525| 5777
> RTD| -4525| -4444| -565| 0| -4525| 5777
> RTD| -4525| -4444| -1656| 0| -4525| 5777
> RTD| -4525| -4444| -1979| 0| -4525| 5777
> RTT| 00:00:06
> RTH|----klat min|----klat avg|----klat max| overrun|---klat best|--klat worst
> RTD| -4525| -4444| -2020| 0| -4525| 5777
> RTD| -4525| -4444| -1050| 0| -4525| 5777
> RTD| -4525| -4444| -1616| 0| -4525| 5777
> RTD| -4525| -4444| -1898| 0| -4525| 5777
> RTD| -4525| -4444| -1939| 0| -4525| 5777
> ...
> Well if I set scheduling latency from automatic "0" to "1" I get:
0 means automatic latency compensation (which does not seem to work that
well here, it overcompensates), while 1 effectively means "no
hardware/software scheduling latency" (=> 1 ns). See also help of the
related kernel configuration parameters.
>
> -sh-3.00# ./run -- -T 10 -h -l 5
>
> RTT| 00:00:01
> RTH|----klat min|----klat avg|----klat max| overrun|---klat best|--klat worst
> RTD| 4767| 4929| 15191| 0| 4767| 15191
> RTD| 4767| 4808| 8282| 0| 4767| 15191
> RTD| 4767| 4808| 8080| 0| 4767| 15191
> RTD| 4808| 4808| 7838| 0| 4767| 15191
> RTD| 4767| 4808| 7272| 0| 4767| 15191
> RTT| 00:00:06
> RTH|----klat min|----klat avg|----klat max| overrun|---klat best|--klat worst
> RTD| 4808| 4808| 7555| 0| 4767| 15191
> RTD| 4767| 4808| 7959| 0| 4767| 15191
> RTD| 4767| 4808| 7393| 0| 4767| 15191
> RTD| 4808| 4808| 7191| 0| 4767| 15191
> RTD| 4767| 4808| 7313| 0| 4767| 15191
>
> Is this a bug or feature please? Can someone throw the light?
> Good would be to print the units to the numbers too (ns).
>
That was likely a layout question of the latency tool's output. We could
simply dump something like "All latencies in nanoseconds" during
start-up. Would this be more helpful?
Jan
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next prev parent reply other threads:[~2006-02-28 12:33 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-27 16:12 [Xenomai-help] negative values of latency/klatency Rudolf Marek
2006-02-28 12:33 ` Jan Kiszka [this message]
2006-02-28 12:52 ` Philippe Gerum
2006-02-28 13:02 ` Philippe Gerum
2006-02-28 14:13 ` [Xenomai-core] " Jan Kiszka
2006-02-28 15:22 ` Philippe Gerum
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