Keith Packard wrote:
> On Mon, 2008-05-19 at 20:11 +0100, Keith Whitwell wrote:
>
>
>> I'm still confused by your test setup... Stepping back from cache
>> metaphysics, why doesn't classic pin the hardware, if it's still got
>> 60% cpu to burn?
>>
>
> glxgears under classic is definitely not pinning the hardware -- the
> 'intel_idle' tool shows that it's only using about 70% of the GPU. GEM
> is pinning the hardware. Usually this means there's some synchronization
> between the CPU and GPU causing each to wait part of the time while the
> other executes. I haven't really looked at the non-gem case though; the
> numbers seem similar enough to what I've seen in the past.
>
>
>> I think getting reproducible results makes a lot of sense. What
>> hardware are you actually using -- ie. what is this laptop?
>>
>
> This is a Panasonic CF-R4.
>
>
So we were actually using a slightly stale version of GEM from Eric's
repos, Michel rerun his tests with the indicated versions without any
significant changes.
I've rebuilt on a HP (Compaq) nx 7300 laptop, 1GB single-channel i945G,
Celeron M [EMAIL PROTECTED] GHz. Kernel 2.6.25rc4. This is the third system we
test.
I've added the "teapot" demo, since it should be completely CPU-bound,
even on this machine.
After the tests, I must say Keith Whitwell's conclusions seem to hold:
* Intel's TTM and GEM's approaches to buffer management translate to
a lot extra CPU usage and worse performance
* With that approach, GEM might improve over TTM, but it's not seen
here.
* Classic is apparently doing suboptimal syncs that limits its
performance in some cases (gears, teapot and perhaps openarena),
one should not benchmark framerates against classic in those cases.
And furtermore
* GEM's tex(sub)image (map and copy to device) performance really
sucks. It would be good to see some benchmarks using pwrite here.
Gears:
Classic 845fps @ 35%
Intel TTM 942fps @ 61%
GEM 902fps @ 61%
i915tex (TTM) 977fps @ 40%
Openarena + exec anholt @ 640x480
Classic 49.8fps 12.3u 1.1s
Intel TTM 54.0fps 12.9u 4.6s
GEM 50.3fps 12.0u 4.8s
i915tex (TTM) 61.0fps 12.6u 1.7s
Ipers without help screen
Classic 333000 pps
Intel TTM 254000 pps
GEM GPU lockup
i915tex (TTM) 325000 pps
Teapot
Classic 65.5 fps (CPU at 77%)
Intel TTM 70.3 fps
GEM GPU lockup
i915tex (TTM) 77.0 fps
Texdown + subimage
Classic 452 + 510 MB/s
Intel TTM 537 + 158 MB/s
GEM 385 + 86 MB/s
i915tex (TTM) 1185 + 1664 MB/s
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