Re: [Xenomai-help] Xenomai installation: high latencies

[Jan Kiszka <jan.kiszka@domain.hid>]

On 2011-12-02 16:28, Kurt Geebelen wrote:
> Dear all,
> 
> I've tried installing Xenomai, following these instructions:
> 
> http://www.xenomai.org/index.php/Building_Debian_packages
> 
> but then for the latest version (xenomai 2.6.0, and kernel 2.6.38.8 and
> for 64 bit) .
> 
> For configuring the kernel, I followed these instructions:
> 
> http://www.xenomai.org/index.php/Configuring_x86_kernels
> 
> All that is stated on these websites works without problems, and I am
> able to boot in the installed xenomai kernel. However, when I perform
> the latency-test (latency in /usr/lib/xenomai), I get latencies of more
> than 1400 microseconds.

Sounds like wbinvd (cache flushing on DMA remappings).

> 
> The system I have is the following:
> 
> Dell™ Precision™ T1500
> One® Intel™ Core i7-860 (2.8GHz, 8MB L3, 95W, Quad Core)
> 6GB DDR3 non-ECC Memory (1333MHz, 3x2GB)
> 512MB PCIe x16 NVIDIA Quadro FX 580 Graphics Card

Do you use the nvidia binary driver? It's known to kill latencies.


> Intel Solid-State Drive 320 Series 120GB
> 
> I have tried reinstalling the kernel several times, but I always end up
> with high latencies.
> I also have consulted with others, who followed the same guidelines as I
> did, and their latencies are about 100 times lower.
> 
> Is there somebody who knows what the problem might be? Might it be a
> hardware-related problem?
> 
> Many thanks in advance,
> Best regards,
> Kurt Geebelen

Jan

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