roland Tollenaar wrote:
> Hi Wolfgang, Gilles, Stephane
>
> In the intrim I have checked for latency killers and have found
> nothing. I have a faster machine than you have posted the poerformance
> of below yet I have substantially worse latencies.
>
> Attached is my config file if you care to look at it.
>
> One point may be USB. I am using usb pen drives and have seen in one
> of the threads that USB (even if not used?) is considered a latency
> killer.
>
> Gilles suggested also to turn off the debug features but they were
> turned off already AFAIK.
>
> Sorry for the delay, I have not been able to work on this project for a
> while.
>
> Ah and I have updated to 2.3.1 today, no problems but also no
> improvement on the latency unfortunately. Just to eliminate that
> point.
The latency killers:
- SMI: check dmesg to see if you get a warning saying that an
SMI-enabled chipset was detected. If yes, read the TROUBLESHOOTING. If
no, and you have a fairly recent Intel chipset, then we probably need
to add support for your chipset to the SMI workaround module, send us
the result of lspci -vv.
- USB: disable legacy USB in BIOS configuration, sometimes it is not
enough, and you have to _enable_ USB in kernel configuration, and load
the USB modules (that is at least uhci-hcd, ohci-hcd, ehci-hcd and
usbcore) so that they disable BIOS legacy USB emulation.
- X-window: if you see high latencies only when the X server is running,
the X-server is probably causing them. A workaround is proposed in the
TROUBLESHOOTING file.
In case all that fails, enable the I-pipe tracer, run latency with the
-f option, and check /proc/ipipe/trace/frozen once you observed the high
latency in latency.
--
Gilles Chanteperdrix.
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