|From:||Keith Packard <keithp-AT-keithp.com>|
|To:||Keith Whitwell <keith-AT-tungstengraphics.com>|
|Subject:||Re: i915 performance, master, i915tex & gem|
|Date:||Mon, 19 May 2008 11:00:50 -0700|
|Cc:||Dave Airlie <airlied-AT-linux.ie>, Ian Romanick <idr-AT-us.ibm.com>, DRI <dri-devel-AT-lists.sourceforge.net>|
On Mon, 2008-05-19 at 05:09 -0700, Keith Whitwell wrote: > I > think the latter is the significant result -- none of these experiments > in memory management significantly change the command stream the > hardware has to operate on, so what we're varying essentially is the > CPU behaviour to acheive that command stream. And it is in CPU usage > where GEM (and Keith/Eric's now-abandoned TTM driver) do significantly > dissapoint. Your GEM results do not match mine; perhaps we're running different kernels? Anything older than 2.6.24 won't be using clflush and will instead use wbinvd, a significant performance impact. Profiling would show whether this is the case. I did some fairly simple measurements using openarena and enemy territory. Kernel version 2.6.25, CPU 1.3GHz Pentium M, 915GMS with the slowest possible memory. I'm afraid I don't have a working TTM environment at present; I will try to get that working so I can do more complete comparisons. fps real user kernel glxgears classic: 665 glxgears GEM: 889 openareana classic: 17.1 59.19 37.13 1.80 openarena GEM: 24.6 44.06 25.52 5.29 enemy territory classic: 9.0 382.13 226.38 11.51 enemy territory GEM: 15.7 212.80 121.72 40.50 > Or to put it another way, GEM & master/TTM seem to burn huge > amounts > of CPU just running the memory manager. I'm not seeing that in these demos; actual allocation is costing about 3% of the CPU time. Of course, for this hardware, the obvious solution of re-using batch buffers would eliminate that cost entirely. It would be nice to see the kernel time reduced further, but it's not terrible so far. -- firstname.lastname@example.org ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ -- _______________________________________________ Dri-devel mailing list Driemail@example.com https://lists.sourceforge.net/lists/listinfo/dri-devel
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