<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW --- - Segfault in glBufferSubData" href="https://bugs.freedesktop.org/show_bug.cgi?id=82683#c9">Comment # 9</a> on <a class="bz_bug_link bz_status_NEW " title="NEW --- - Segfault in glBufferSubData" href="https://bugs.freedesktop.org/show_bug.cgi?id=82683">bug 82683</a> from <a class="email" href="mailto:itoral@igalia.com" title="Iago Toral <itoral@igalia.com>"> Iago Toral</a> <pre>(In reply to <a href="show_bug.cgi?id=82683#c6">comment #6</a>) (...) > Frankly, I'm a bit loathe to fix these, as it adds overhead (even if not > much) to well behaved applications, to try and provide a better error report > to applications which are clearly broken. Most applications don't even try > to handle GL_OUT_OF_MEMORY, because in order to notice, they'd have to call > glGetError() after virtually every API call...which is a widely known way to > make your application horribly slow. Without doing that, you don't know > what API calls actually failed, so how can you recover from it? And even if > you know exactly what failed...you still have to be able to stop what you're > doing, delete a bunch of things, and recover sensibly...which is a pretty > heroic task. FWIW, I totally agree with this. (In reply to <a href="show_bug.cgi?id=82683#c7">comment #7</a>) > Sorry, can someone help me understand how this did turn out to be an OOM > issue? > > At 128000 buffers x 2^7 bytes per buffer, I get segfaults. > At 64000 buffers x 2^14 bytes per buffer, it completes fine. > At 64000 buffers x 2^15 bytes per buffer, the OS kills the program for using > too much RAM. It says "Killed". It doesn't segfault. >From the results, it seems like the kernel drm module has some limit on the number of buffers it can allocate. Indeed, if I reduce the size of the data to a single float per buffer it still segfaults at 128000 buffers. At least on my SNB, the limit is close to 2^16 (65536 buffers). It starts to segfault a bit before that (around 65300) but I guess that is probably because other apps in my desktop and the desktop itself are also allocating buffers from the driver.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> </ul> </body> </html>