<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - Textures binded to framebuffer objects or images are not correctly updated." href="https://bugs.freedesktop.org/show_bug.cgi?id=110229#c14">Comment # 14</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - Textures binded to framebuffer objects or images are not correctly updated." href="https://bugs.freedesktop.org/show_bug.cgi?id=110229">bug 110229</a> from <a class="email" href="mailto:laurentduroisin@gmail.com" title="Laurent <laurentduroisin@gmail.com>"> Laurent</a> <pre>(In reply to Laurent from <a href="show_bug.cgi?id=110229#c13">comment #13</a>) > "I'm afraid that's not the problem. The drivers compile the whole shader, > then copy it to memory, and the entire content is present before the shader > stops executing. This has been extensively battle-tested in many games, > conformance suites, computer-vision analysis, industrial-scale movie > renders, etc." > > Yeah but the shader'll not stop if he's not launched, and you have to use > some synchronisation mechanism to copy the content before the shader stops. > > > "The real answer is that maintaining these drivers is a lot of work, and the > people developing it cannot always drop everything to examine your source > code and debug a relatively complex application for you in the space of a > few days." > > Yes of course. > > "GPU execution is very, very, different from CPU execution: in particular, > fragment shading is massively parallel (frequently within tiles). It may be > that the execution order is not what you expect, or the access to shared > variables is also not what you expect. It's hard to tell from the code, > since the per-fragment linked-list approach you have is definitely ... > novel." > > Yeah so there are one thread per fragment and not per instruction. > With the CPU you need mutex to avoid concurrent access, and I think two CPU > thread cannot write/read to/from the memory at the same time, the GPU can > because he use one micro controller per thread (if I'm not wrong) so you > don't need to protect from concurrent access but you need to use an OIT > mechanism in the driver (I think) because you don't know which thread'll > write to the memory first... And (I've forgot), using mutex is slow so, normally we don't use them with the GPU.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> </ul> </body> </html>