To answer your question directly: no, you should not need to access the files in any particular order. It should be able to handle thousands of texture files totalling many hundreds of GB without trouble. When you post the other info I suggested, I think we'll have more specific advice to offer.
Two more questions: 1. What is your access pattern like? Is it *completely* incoherent, like every single query is at a completely random location and file compared to the previous one? Or is there any coherence at all? 2. Are you supplying correct derivatives to your texture calls (dsdx, dtdx, dsty, dtdy)? On Sep 10, 2014, at 2:59 PM, Simon Smith <[email protected]> wrote: > Hi guys, > > OK, I’m looking for some Best Practices and Do’s/Dont’s when using the OIIO > system to manage textures and give simple access to the texture pixel values > as and when needed. > > The problem is that we’re currently not getting the performance I might have > expected once we start to use only a few input images. We are essentially > using multiple 4k EXR’s and sampling them pretty much across their entirety > during the process, but not linearly (as in, we might sample from multiple > textures for each final pixel calculation). > > What I’m finding is that once we start using only 3 or 4 of these with the > high level texture system, the performance drops off dramatically. > > I did test converting them to tx files (thinking that it would use just the > lower mipmaps thus give better performance) but that did not seem to make any > difference, so obviously we are doing something very wrong! > > Before I went diving into the codebase to see what is happening I thought I’d > just run a quick email by you guys who know how best to use the systems. > > Should we be trying to only utilise one texture at a time perhaps, or should > we be setting some of the texture system attributes to better utilise the > system. When requesting pixel data from textures are there things we should > be thinking about tailored to our situation so that the system runs smoothly. > Should we actually not be using the higher level texture system but rather > getting more down-and-dirty with the lower image level functionality. > > Apologies for the raft of questions, but i’m 90% sure we are having the > issues we are because we are not using the system properly, so hopefully you > can share some pearly words of wisdom with me :) > > > Best Regards, > Simon. > > _______________________________________________ > Oiio-dev mailing list > [email protected] > http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org -- Larry Gritz [email protected]
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