IRC log for #brlcad on 20170206

00:39.31 *** join/#brlcad kintel (~kintel@unaffiliated/kintel)
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16:31.44 Notify 03BRL-CAD:starseeker * 69397 (brlcad/trunk/NEWS brlcad/trunk/src/rt/viewweight.c): Have rtweight's loading of .density file use BU_DIR_SEPARATOR define.
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19:35.49 Apra brlcad: Hey the channel seems to be quite empty :)
19:42.57 Apra anyways what are your plans about this years gsoc?
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20:18.48 *** join/#brlcad Stragus_ (~alexis@modemcable090.29-19-135.mc.videotron.ca)
20:23.32 *** join/#brlcad kintel (~kintel@unaffiliated/kintel)
20:37.14 ``Erik hw.byteorder: 1234
20:37.20 ``Erik the world seems right again O.o
20:38.07 ``Erik hrm, scratch that, the x86 says the same thing, hopefully I didn't accidently put this thing in lil' endian mode
20:50.31 Stragus Playing on ARM?
20:56.07 ``Erik yeah, it's my new 'main' server, a rpi2 replaced the old thunderbird
20:56.11 ``Erik FreeBSD fenris 12.0-CURRENT FreeBSD 12.0-CURRENT #0 r313175: Mon Feb 6 08:06:12 EST 2017 erik@rpi2:/mnt/da0s1/usr/obj/mnt/da0s1/usr/src/sys/RPI2 arm
20:56.41 Stragus I absolutely love ARM. Neon is wonderful
20:57.04 ``Erik O.o just a few years ago, you said arm was crap and it was all about amd64 :D
20:57.15 Stragus I said that? Darn :(
20:57.46 Stragus That was before I discovered Neon surely, but that still surprises me
20:58.19 Stragus NEON is everything MMX/3dnow!/SSE/SSE2/SSE3/SSSE3/SSE4.1/SSE4.2/AVX/AVX2 should have been... implemented properly right away, on the first shot
20:58.31 ``Erik iirc, we were chatting about server farms and your focus at the time was sse heavy C
20:58.44 ``Erik erm, and tons of x86 asm *shudder* :D
20:58.59 Stragus Eheh, so definitely before I discovered Neon
21:00.01 ``Erik I wonder how neon compares to, say, altivec
21:00.15 ``Erik (cuz altivec was everything that mmx/3dnow/sse*/etc was supposed to be)
21:00.54 Stragus Right... I read the Altivec docs but never used it. But Neon has some amazing stuff you won't find in Altivec either, as far as I know
21:01.02 ``Erik Stragus: one of the projects I'm sorta attached to has an rpi3 driving a tx1 in a mobile package O.o pheer
21:02.08 Stragus Neon can read a bunch of 16 floats (xyzw,xyzw,xyzw,xyzw), de-interleave and store in 4 separate registers (xxxx,yyyy,zzzz,wwww). And that's a... single cheap instruction
21:02.39 Stragus It's just fantastic, everything people need to do in real life
21:04.03 ``Erik interesting, but why not ship that to the gpu?
21:05.27 Stragus Sure, CUDA is also fabulous... 32-wide SIMD with fast scattered loads/stores, per-lane predicates and branching, on-chip shared memory, hardware switching to other threads whenever waiting for *anything*
21:05.30 Stragus CPUs suck :p
21:06.06 Stragus Still, in the realm of CPUs, ARM NEON does a pretty good job
21:08.04 ``Erik (I'm still saddened that the rpi is setting the arm to LE, and doubt the port is good enough to do BE)
21:08.53 ``Erik but it replaces a noisy powerhungry slow pos and seems to be doing a solid job so far, so *shrug* :)
21:08.59 Stragus I think the world is setlling on little endian, just like it settled on bytes being 8 bits
21:09.17 Stragus settling*
21:09.40 ``Erik bleh, VHS instead of beta, bluray instead of hddvd or whatever, ...
21:10.20 *** join/#brlcad kintel (~kintel@unaffiliated/kintel)
21:11.02 ``Erik I wonder if BRL-CAD will run on it... I bet it'll perform like complete crap in the benchmark :D
21:12.17 Stragus Eheh. I'm not aware of optimization advantages to big endian, perhaps I'm missing something...
21:13.07 ``Erik the only advantage of big endian is that I'm old and back in the day, the cool machines all used big endian, so now I'm sitting here shaking my cane and remembering the good old days
21:13.17 ``Erik y'know, make 'murika grrt agn
21:13.34 Stragus Oh, right, of course! :)
21:14.49 ``Erik the 'server room' is now very quiet, however, with the multiple fans and old 20g 5400 shut down, the only moving part is the pidrive
21:15.17 ``Erik which is basically just a laptop drive with some modified plugs and less case
21:15.18 Stragus is trying to think of any optimization only possible on big endian...
21:17.20 ``Erik the only real advantage is converting to/from network order (noop)
21:18.34 ``Erik iirc, even simple things like an adder uses a few less transistors in big endian, so there's a cost in silicon real estate... though the arm (and several other more modern chips) have switchable endian
21:18.41 Stragus I was trying to think of rather inherent advantages
21:19.49 Stragus Ahah, Google found something! memcmp() on big-endian is more efficient (assuming aligned pointers, etc.)
21:23.06 ``Erik when you do neon stuff, is that in asm, or is there an intrinsics package or api or something?
21:23.38 Stragus They have intrinsics. The compilers don't do a good job though, so people often rely on inline assembly
21:24.01 Stragus SSE/AVX has received more loving care in GCC than Neon
21:24.48 Stragus Have a look at arm_neon.h
21:26.36 ``Erik hm, not part of my clang distro :)
21:28.28 ``Erik not in the raspbian image, either... ah well, if I get to needing it, I'll find it
21:32.11 Stragus Feel the call of GCC, it's claiming for you
21:38.39 ``Erik swift! sbcl!
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21:52.27 Notify 03BRL-CAD:starseeker * 69398 brlcad/trunk/src/external/CREO/creo-brl.cpp: Next problem is in assemblies - got a crasher in here somewhere.
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