Am 29.11.2016 um 17:21 schrieb Andrew A.: >> Am 29.11.2016 um 15:18 schrieb Jose Fonseca: >>> Actually, IIUC https://github.com/divVerent/s2tc/wiki/libtxc_dxtn picks >>> colors at random, so its possible you have the same version of s2tc >>> library, but random colors are being picked. >>> >>> If so, you might to hack s2tc to not pick colors at random, or just >>> avoid S3TC textures if you can. >>> >> >> IIRC the "randomness" had no actual random bits in it, so as long as the >> same library is used on both machines the results should be the same. >> Albeit from the pictures it indeed looks like one has full decoding and >> the other not (it's not jist the obvious issues on the "D" but it's not >> quite smooth elsewhere neither). >> >> (Albeit I'm not quite sure if you have similar cpus, the E3-1275 v3 is >> Haswell which has AVX2, the CPU E5-2673 v3 doesn't seem to exist or at >> least it's not in intel's database - if that's a v2 instead it would be >> Ivy Bridge lacking AVX2, just featuring AVX1. In this case you can still >> get slightly different results from texture sampling due to potentially >> different choice of AoS vs. SoA sampling, albeit nothing which would >> explain what you're seeing unless there's a bug somewhere...) >> >> Roland > > The problem was indeed different versions of libtxc being used, so I > settled on using a consistent version of that library across the > systems, and now all is well. > > I'm not sure why the 2673v3 is not in the arc, but whatever it is, > /proc/cpuinfo confirms it supports avx2. > The closest I could find in the ARC is: > http://ark.intel.com/products/81709/Intel-Xeon-Processor-E5-2670-v3-30M-Cache-2_30-GHz > Perhaps this 2673v3 was a stepping only shipped to customers like > MS/Amazon for use on Azure/AWS, but that's just a hunch. Ah ok.
> By the way, > is there an environment variable to lock mesa/llvmpipe to use AVX1 and > not AVX2? Nope. If you want to disable certain features like avx2 you need to set has_avx2 to 0 in lp_build_init() (src/gallium/auxiliary/gallivm/lp_bld_init.c). (If you want to guarantee identical results between machines supporting AVX and AVX2, you'd almost certainly also want to disable fma too). Messing with these flags is actually a bit hackish, and I'm not sure there's generally much benefit exposing them (since just "avx" isn't really all that useful, and there's quite a few flags, some of which depend on others). Since you mentioned you run it in a VM, in this case it might be possible to limit the cpu capabilities which are exposed to the guest easily. Roland _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
