This has been a long problem with Compiz that NVIDIA never fixed,
intermittent performance problems such as hick ups; the problem is easily
reproducible moving the cursor while opening programs such as Firefox or
Evolution.
Until Compiz 0.3.4 this bug was fixed setting the __GL_YIELD environment
variable to "NOTHING" in Compiz environment.
the only thing that this changes (and is supposed to change) is to make
compiz responsive under high cpu load.
Since Compiz 0.3.6 setting the __GL_YIELD environment variable to
"NOTHING"
is not enough, but launching Compiz WITHOUT "--unredirect-rendering"
is also
needed to fix this. So whats the problem using direct-rendering? using
direct-rendering triggers the NVIDIA vterm switching bug, that makes the
screen keep black on vterm switching. If one clicks at the black
screen, a
hard reboot is needed; the only solution is to kill X and start it again.
Turn of sync to vblank this might be causing this.
Also, for some people like me, using --indirect-rendering gives better
performance than using direct rendering.
no its not!
if you use indirect rendering on nvidia the _GL_YIELD env variable will
gets ignored and the system will be almost unuseable under high load.
I can confirm the problem, although it does not happen regularly for me --
-- sometimes compiz crashes with a SEGFAULT instead and sometimes all
continues to work normally after a few VT switches. For that reason, I'm
using --indirect-rendering by default and have few experience with the
opposite.
I have turned on the DEBUG macro and found my terminal is filled by a flood
of messages like this:
X Error of failed request: BadValue (integer parameter out of range for
operation)
Major opcode of failed request: 128
Minor opcode of failed request: 16
Resource id in failed request: 0x20de
every now and then when direct rendering is used. However, I can't tell
where such message comes from, because the minor opcode of 16 doesn't
mean anything useful: X_GLXVendorPrivate. I think this can very well cause
the slowdown, but the VT switching bug probably not.
Note: Turning off Sync to VBlank seems only to attenuate the latter.
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