On 02/26/2011 03:09 AM, Michel DÃnzer wrote:
On Fre, 2011-02-25 at 12:11 -0500, Phillip Susi wrote:
It seems like the GPU is executing a few different microcode kernels
that process commands placed into ring buffers. When the ring buffers
are empty and the gui is idle, it seems like the GPU is still busily
executing an infinite loop checking for work in the ring buffers.
As has been pointed out by Alex, that's not true to the best of our
knowledge.
I wonder how that is though. I see nothing in the R600 microcode
documentation about a way to halt execution, and it explicitly says it
does not support interrupts, so I don't see any way for the CP to avoid
busy waiting other than to be explicitly stopped by the driver.
Shouldn't the driver detect the idle condition and issue an
r600_cp_stop() to halt execution and stop wasting power?
Feel free to try it, but I wouldn't expect it to make much if any
difference.
I tried adding a debugfs file to call it and it didn't seem to make any
difference.
Did you check that your card runs significantly cooler in the other OS
before starting all this ruckus? (Though even if it does, the lack of
clock gating might explain the difference)
I don't even have a working copy of the other OS any more. It is on my
old first gen WD raptor fakeraid 0 that the new system's bios and
Windows driver won't recognize. Now that you mention it though, I do
think it always tended to run hot there and I usually underclocked it a
bit to try and help. Maybe I just have a poorly designed card with
insufficient heatsink+fan?
It seems like clock gating, while helpful to maximize power savings,
should not be needed to stay below critical temperatures when idle.
Strange. This morning it seems to be running at "only" 66 C instead of 80+.
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