Hello again,
well disabling acceleration in XFree 4.0.1 caused a maxium latency of
about
10usec when moving windows and typing enter key , which caused about 15
- 50 msec (mili, not micro)
delays with acceleration enabled . The result is ofcourse that X crawls
, moving windows is dead slow,
but that is to expect without hardware acceleration. There are some
other parameters to tune for the
s3 driver, they have to do with the pixel FIFO, and maybe that works to.
but big warning to all , when using X, double check yer realtime
latencies, cause they could
be very bad. (and with XFree 4.0.x even worse)
Although it probably also depends on the videocard, mine is a crappo one
with s3virge chipset, i will
try with a G400 when i have it (somewhere next week).
Thanx all that helped and pointed in the right direction.
BTW i am still interested to hear from other ppl if they ran into
problems with XFree 4.0.1, cause
slowly 4.0.x is appaering on the distributions (like RH 7 and SuSe 7).
Thanx again, and off to bed its 2:30AM and i have to work again tomorow
:-)
- Erwin
John Regehr wrote:
>
> > > My suggestion is that you recompile X with this macro set to false - so that X
>doesn't
> > > try to disable irqs and see if that fixes your problem. I suspect that this is
>not
> > > your problem.
> >
> > You are correct that it is probably not the dissabling of interruprts
> > that is the problem, bacuse that is only used in a few places (the ATI
> > driver and in SupperProbe) and only to do the clockprobing.
>
> Video drivers can hose RTLinux/RTAI by writing to a command FIFO on the
> video board without first checking if it's full. In the past some
> Windows drivers have done this as an "optimization" (it speeds up the
> common case by eliminating a PCI read). A write to a full FIFO will
> stall the PCI bus (and the rest of the machine) - this condition can
> last for many milliseconds.
>
> I don't know if this is what you're seeing, but it is consistent with
> low RTL latency on a quiet box and high RTL latency when you drag a
> window around. The stream of blits generated by dragging a window can
> easily fill up a command FIFO.
>
> If this is the case, the solution is to either convince the driver
> writers that they are doing something wrong, or if that doesn't work
> then distribute patches and warn the RTL community about which drivers
> misbehave.
>
> John Regehr
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