[PATCH, REALTIME] nvidia-1.0-8762 and Linux-2.6.16-rt23

[JaXXoN]

Hi!

Please find attached a patch for the nvidia glue sources
to get realtime preemption working with the latest nvidia
graphics drivers and Linux realtime preemtion kernel versions.
There have basically been no changes since the previously
tested 1.0-8756/2.6.16-rt16 combo.


Know limitations:

In my single core ("maxcpus=1") high resolution timer enabled
setup, a running glxgears window can easily freeze the X-Server
for about three seconds when being moved around. This "three
seconds glxgears sticky" problem has been discussed earlier
in this forum. For me, the problem goes away when either
disabling HRT support or when the system operates in dual core
mode (SMP with two cores).

The patch disables PAT support by default to avoid high
latencies of several hundred microseconds caused by a
"wbinvd" instruction (cache flush) when starting or stopping
3D applications. However, disabling PAT support can have negative
impacts on 3D performance. If latencies below one millisecond
are ok for your application (i.e. pro-audio), you may
re-enable PAT support by applying "nv_disable_pat=0"
as parameter for the nvidia kernel module (or change the
default value of this parameter in file "nv.c" at line 47).

Please note that the nforce4 SATA controller can cause
latencies up to 16.6 milliseconds, probably due to
"SMM BIOS calls". The only solution i found to get around
that problem was to use a different HDD controller (SIL3114),
instead. I didn't checked if the nforc4 "standard" ATA
(non-SATA) controllers are also affected.

regards

Bernhard

[fzu]

still OK for 2.6.17-rt1.

Thanks