On 22.01.2010 17:41, Keith Whitwell wrote: > Christoph, > > The vertex usage issue is a bug and can be fixed. > > Oh ... I thought it was intentional, and relied on it to decide whether to use immediate mode or to copy the buffers to VRAM/GART first. That bug helped increase nexuiz' FPS tenfold ... :'( > It sounds like you're really asking for another flag that indicates the > expected lifetime of the buffer. That sounds orthogonal to the ones we > already have describing the possible binding points. > > I suspect ttm is already reusing buffer memory for you (userspace > sub-allocation), so the weight of the ttm calls you are making may be less > than you suspect. > > Keith > ________________________________________ > From: Christoph Bumiller [e0425...@student.tuwien.ac.at] > Sent: Friday, January 22, 2010 8:35 AM > To: Keith Whitwell > Cc: Michal Krol; mesa3d-dev > Subject: Re: [Mesa3d-dev] [RFC] gallium-multiple-constant-buffers merge > > On 22.01.2010 17:01, Keith Whitwell wrote: > >> Christoph, >> >> The USAGE_CONSTANT flag is a bit confusing -- the intention is to state that >> this buffer can be bound as a constant-buffer, not that it is itself >> immutable. It should be perfectly legal to create a single constant buffer >> and update it over time... >> >> >> > I didn't interpret the USAGE_CONSTANT as meaning the buffer's contents > should be constant at all, I just meant it should not be used for throw-away > constant buffers. > The same is done for vertex buffers created for glVertexPointer etc., they > do NOT have PIPE_BUFFER_USAGE_VERTEX (they are user_buffer_create), > but STILL get set as vertex buffers. > > Alternatively, rather than not using USAGE_CONSTANT/VERTEX on those, > we could finally add PIPE_BUFFER_USAGE_STATIC,STREAM,THROW_AWAY ... > > Of course, maybe we shouldn't take the buffer_create function literally and > ask TTM to create a new buffer object every time it's called ... I admit > that > this whole thing is a pipe driver specific issue. > >> Keith >> ________________________________________ >> From: Christoph Bumiller [e0425...@student.tuwien.ac.at] >> Sent: Thursday, January 21, 2010 3:48 PM >> To: Michal Krol >> Cc: mesa3d-dev; Keith Whitwell >> Subject: Re: [Mesa3d-dev] [RFC] gallium-multiple-constant-buffers merge >> >> On 21.01.2010 20:20, michal wrote: >> >> >>> Hi, >>> >>> This simple feature branch adds support for two-dimensional constant >>> buffers in TGSI. >>> >>> An example shader would look like this: >>> >>> FRAG >>> >>> DCL IN[0], COLOR, LINEAR >>> DCL OUT[0], COLOR >>> DCL CONST[1][1..2] >>> >>> MAD OUT[0], IN[0], CONST[1][2], CONST[1][1] >>> >>> END >>> >>> For this to work, one needs to bind a buffer to slot nr 1 containing at >>> least 3 vectors. >>> >>> >>> >>> >> I've been thinking about what to do with these multiple constant >> buffers now, and I thought we might want to avoid creating those >> buffers with PIPE_BUFFER_USAGE_CONSTANT that will be used >> only once and then discarded, as the currently used uniform buffer >> is. >> Instead it should only be set for persistent ones that the user >> created with glGenBuffers'd etc. (this would be similar to our usage of >> PIPE_BUFFER_USAGE_VERTEX). >> >> Then I would be able to decided whether to put them in VRAM or >> in user memory (since creation of VRAM buffers is a bit costly), >> and then either copy/upload constants from the buffer if it's user, >> or bind it's GPU virt. address to the program CB it if it's VRAM. >> >> Of course, I don't know if it would even be noticeable performance-wise >> if I just kept around a bunch of buffers and pushed constants all the >> time ... >> >> Any thoughts ? >> Thanks, >> Christoph >> >> >>> ------------------------------------------------------------------------------ >>> Throughout its 18-year history, RSA Conference consistently attracts the >>> world's best and brightest in the field, creating opportunities for >>> Conference >>> attendees to learn about information security's most important issues >>> through >>> interactions with peers, luminaries and emerging and established companies. >>> http://p.sf.net/sfu/rsaconf-dev2dev >>> _______________________________________________ >>> Mesa3d-dev mailing list >>> Mesa3d-dev@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/mesa3d-dev >>> >>> >>> >> >
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