On 5 April 2017 at 18:55, Daniel Vetter <dan...@ffwll.ch> wrote: > On Wed, Apr 05, 2017 at 04:38:25PM +0100, Emil Velikov wrote: >> Hi Ken, >> >> On 5 April 2017 at 01:09, Kenneth Graunke <kenn...@whitecape.org> wrote: >> > Hello, >> > >> > This series imports libdrm_intel into the i965 driver, hacks and >> > slashes it down to size, and greatly simplifies our relocation >> > handling. >> > >> > Some of the patches may be held for moderation. You can find the >> > series in git here: >> > >> > https://cgit.freedesktop.org/~kwg/mesa/log/?h=bacondrm >> > >> > A couple of us have been talking about this in person and IRC for >> > a while, but I realize I haven't mentioned anything about it on the >> > mailing list yet, so this may come as a bit of a surprise. >> > >> > libdrm_intel is about 15 source files and almost 13,000 lines of code. >> > This series adds 3 files (one .c, two .h) and only 2,137 lines of code: >> > >> > 60 files changed, 2784 insertions(+), 647 deletions(-) >> > >> > The rest of the library is basically useless to us. It contains a lot >> > of legacy cruft from the pre-GEM, DRI1, or 8xx/9xx era. But even the >> > parts we do use are in bad shape. BO offset tracking is non-threadsafe. >> > Relocation handling is way too complicated. These things waste memory, >> > burn CPU time, and make it difficult for us to take advantage of new >> > kernel features like I915_EXEC_NO_RELOC which would reduce overhead >> > further. The unsynchronized mapping API performs a synchronized mapping >> > on non-LLC platforms, which can massively hurt performance on Atoms. >> > Mesa is also using uncached GTT mappings for almost everything on Atoms, >> > rather than fast CPU or WC maps where possible. >> > >> > Evolving this code in libdrm is very painful, as we aren't allowed to >> > break the ABI. All the legacy cruft and design mistakes (in hindsight) >> > make it difficult to follow what's going on. We could keep piling new >> > layers on top, but that only makes it worse. Furthermore, there's a >> > bunch of complexity that comes from defending against or supporting >> > broken or badly designed callers. >> > >> I believe I mentioned it a few days ago - there is no need to worry >> about API or ABI stability. >> >> Need new API - add it. Things getting fragile or too many layers - sed >> /libdrm_intel$(N)/libdrm_intel$(N+1)/ and rework as needed. >> >> I fear that Importing libdrm_intel will be detrimental to libva's >> intel-driver, Beignet and xf86-video-intel development. >> Those teams seem to be more resource contained than Mesa, thus they >> will trail behind even more. >> >> As an example - the intel-driver is missing some trivial winsys >> optimisations that landed in Mesa 3+ years ago. That could have been >> avoided if the helpers were shared with the help of >> libdrm_intel/other. > > That is kinda the longer-term goal with this. There's a lot more that > needs to be done besides Ken's series here, this is just the first step, > but in the end we'll probably move brw_batch back into libdrm_intel2 or > so, for consumption by beignet and libva. > > But for rewriting the world and getting rid of 10+ years of compat > garbage, having a split between libdrm and mesa isn't great. > So the goal is to have the code in mesa as a form of incubator until it reaches maturity. This way one will have a more rapid development and greater flexibility during that stage.
If I misunderstood you correctly and the above sounds right - then the idea is amazing. Silly me did not click while reading the summary email. Thanks Emil _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
