CppCon 2016: Bryce Adelstein Lelbach “The C++17 Parallel Algorithms Library and Beyond"

[@KurtDonkers]

I dont know if this is me just having a positive focus day, but I found this was a really instructive, clear talk. Well done for a subject this 'dry'.

[@CellularInterceptor]

Brilliant presentation, Bryce!!! I work extensively in parallel signal processing applications - very useful. Thank you for sharing!

[@TruthNerds]

Glaring mistake at 18:15 : GNSUM requires an associative operation. GSUM requires an associative *and* commutative operation. *Neither* function is "fine for a non-associative op". Remember: associativity of op means that op(op(a,b),c) == op(a,op(b,c)) commutativity of op means that op(a,b) == op(b,a) IOW, if the operation is associative, you are allowed to reorder *applications* of the operation. If the operation is commutative, on the other hand, you are allowed to reorder *operands* . GSUM assumes it is allowed to do both.

[@TruthNerds]

As a side note, here are some operations that are associative but not commutative (i.e. they could be used with GNSUM, but not GSUM): - function composition (if you are into higher order functional programming) - multiplication of matrices, or of quaternions (if you are into scientific number crunching) - probably most practically, concatenation Operations that are commutative but not associative are fairly rare. One example are boolean NAND and NOR: a NAND b = NOT (a AND b) a NOR b = NOT (a OR b) It is obvious these are commutative, but it is easy to come up with counter-examples to associativity. NAND will be abbreviated as ⊼: 0 ⊼ (0 ⊼ 1) = 0 ⊼ 1 = 1 (0 ⊼ 0) ⊼ 1 = 1 ⊼ 1 = 0

[@TheGokhansimsek35]

Excellent talk.. super clear explanations for the fairly complicated topics.. thanks a lot Bryce !!

[@Fetrovsky]

What's that "urinary" operator he keeps talking about?

[@draguin]

That's funny :D

[@Fetrovsky]

I know, I'm just messing with you, Bryce. :)

[@raymundhofmann7661]

If i am concerned, it is what i use for peeing. It has a high precedence and can be overloaded in ways that are ostracized on some religions/societies/ethnicities, might make you go to hell or might make Allah punish you.

[@TomaszWota]

Well I chuckled when he said that. ;) Urinary operators can piss off.

[@TruthNerds]

IDK, maybe it has something to do with non-binary bathrooms…

[@raymundhofmann7661]

I appreciate to have this in C++ but believe it will not picked up by enough software engineers. I believe the CPU manufacturers are in demand to supply silicon where it is easier to effectively utilize the always increasing number of transistors. It just makes so much more sense to have a new "genius" CPU than to force all software to adapt in a fundamental and exhaustive way or stagnate otherwise. Now that Intel owns Altera turning software engineers into hardware engineers is the last thing that they could demand, just because they are somewhat clueless what to do with the ever increasing integration capability. Again, although it is useful for experts, i think it is not the way that will take off and solve this CPU architecture problem since 2000.