Date: Mon, 16 Jun 2003 14:41:01 -0700 From: Gareth Hughes <gareth@nvidia.com> To: Andy Ritger <ARitger@nvidia.com>, Daniel Eischen <eischen@pcnet.com> Cc: zander@mail.minion.de Subject: RE: NVIDIA and TLS Message-ID: <2D32959E172B8F4D9B02F68266BE421401A6D7CD@mail-sc-3.nvidia.com>
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On Mon, 16 Jun 2003, Andy Ritger wrote: > > So from an OpenGL point of view, here are several alternatives that > I see for atleast the near term: > > - make NVIDIA's OpenGL implementation not thread-safe (just > use global data rather that thread-local data) > > - accept the performance hit of using pthread_getspecific() > on FreeBSD. From talking to other OpenGL engineers, > conservative estimates of the performance impact on > applications like viewperf range from 10% - 15%. I'd like > to quantify that, but certainly there will be a performance > penalty. And these are *very* conservative estimates -- you're essentially adding a function call into a path that is, on average, less than ten instructions per OpenGL API call, where the number of API calls per frame is upward of 3 million (3 calls per vertex, over a million vertices for some Viewperf benchmarks). The API was designed this way for a reason, and fast thread-local storage is a fundamental part of a high performance implementation. -- Gareth Hughes (gareth@nvidia.com) OpenGL Developer, NVIDIA Corporation
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