On 02/17/2014 05:17 PM, Philippe Gerum wrote:
On 02/17/2014 04:56 PM, Christian Göbeler wrote:
Am 17.02.2014 15:24, schrieb Philippe Gerum:
On 02/17/2014 01:57 PM, Christian Göbeler wrote:
Hello everyone,
I'm trying to get xenomai working on my laptop:
- Intel i7-2630QM
- HM67 Chipset
- Ubuntu 12.04
- NVidia GF 540 and Intel onboard graphics chip
- kernel 3.8.13 x86_64
- xenomai 2.6.3
but when I run the latency tests I keep getting high worst case
latencies.
When generating load by manually calling dd or using the "dohell" script
I get
latencies >290. When I start X while running the latency test I get
latencies >700
.. and finally when I run glxgears on the nvidia card I get latencies of
up to >9000.
Eventhough these do only occur right when I start glxgears.
I do not intend to measure latencies while doing 3d animation but I
think the
latencies shown indicate some kind of configuration mistake which I'd
like to
avoid.
If you plan to use the i915 drm driver with an Intel integrated
graphic chip, make sure to run ipipe-core-3.8.13-x86-4, anything
earlier (i.e. 3.8.13-x86-3 and below) shows high latencies.
http://download.gna.org/adeos/patches/v3.x/x86/ipipe-core-3.8.13-x86-4.patch
Thanks for the hint. ipipe-core-3.8.13-x86-4 patch is included in the
xenomai 2.6.3 download and was successfully applied to my kernel so that
should not be the reason for those latency peaks.
Increasing CONFIG_XENO_OPT_SYS_HEAPSZ solved the problem of not being
able to run the switchtest.
Ok. Doing so allowed to pull more thead control blocks out of the system
heap since switchtest creates a truckload of them (for a good reason
though).
But I still have those latency peaks... when I do nothing and simply run
the tests including the dohell script or compiling some code parallel to
the test I get a 200-300 us latency peak about once a minute... but
whenever I activate the discrete graphics card, connect a mouse, insert
a cd, disconnect the power supply or a fan starts to work I instantly
get a latency peak from 300us to 700us ...
Is there anything I can do to prevent this? (besides not touching anything)
How can I find what's causing this?
Maybe you are facing both of the common issues with x86 desktop
hardware: SMI and bad interaction with the graphic support. Assuming
that some of the latency must be triggered by the graphic support given
what you have just described, it may we useful to know whether SMI is
involved as well.
First, you may want to run the latency tests without graphic desktop
(pure console mode, no X), and see how it goes.
If you are using a recent enough distribution, its text mode may in fact
use the framebuffer, so be graphic. In order to boot using the real text
mode (80x25), you may want to blacklist the nouveau driver. On a debian
(wheezy) distribution, you will find examples of blacklisting in
/etc/modprobe.d.
Also, your configuration has some options that you may want to turn off:
CONFIG_PM_RUNTIME
profiling
memory power saving
CONFIG_FTRACE
As for SMI, please check the kernel logs to see if SMIs are really
enabled. If your BIOS has a configuration of the fan, select a "full on"
mode, instead of adaptive mode, as BIOS adaptive mode is most probably
based on SMI.
--
Gilles.
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