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Your comment has made me curious. I tried to think of some examples of performance sensitive apps that aren't amenable to multi-threading and I couldn't, but it

by vilya 13y ago

Your comment has made me curious. I tried to think of some examples of performance sensitive apps that aren't amenable to multi-threading and I couldn't, but it seems like they could offer interesting areas for R&D. Can you share some examples?

Yoric 13y ago
Consider a single tab of a web browser, for instance. By specification, much of the code must run in the same thread. Keeping the semantics while getting code out of the thread is extremely difficult, often impossible. I should know, that's my dayjob :)
- vilya 13y ago
  So the reason you can't make it faster than JavaScript by multi-threading it is... because of JavaScript? :-) I had a look at your profile and it looks like you're doing some very valuable work. I was rather hoping for some examples which didn't involve JavaScript, though.
  - saucetenuto 13y ago
    It used to be that almost all PC games were single threaded. Many still are: Civilization 4, Dwarf Fortress, and Morrowind, for example.
fulafel 13y ago
Many things are hard to parallelize using current technology, and there indeed has been lots of research done on it. History goes back to the supercomputer era (Cray, Connection Machine, Transputer etc.) The term of art is "inherently sequential" problems (vs "embarrassingly parallel"). In addition, the programming effort gets untenable quickly due to Amdahl's law when the amount of parallelism increases. Eg. if you have 100 cores, even if only 1% of work in your program is sequential, your performance goes down the drain. Currently we're in the comfy phase of the curve with few cores... We've been making good progress with parallel-minded reimaginings of programming languages and computer architectures on one front: GPUs. On the CPU we are saddled with the inertia and backwards compatibiltiy lock-in of tools and culture (witness lasting use of C++ as a tool to write parallel software)

by vilya 13y ago

Yoric 13y ago

Consider a single tab of a web browser, for instance. By specification, much of the code must run in the same thread. Keeping the semantics while getting code out of the thread is extremely difficult, often impossible. I should know, that's my dayjob :)

vilya 13y ago
So the reason you can't make it faster than JavaScript by multi-threading it is... because of JavaScript? :-) I had a look at your profile and it looks like you're doing some very valuable work. I was rather hoping for some examples which didn't involve JavaScript, though.
- saucetenuto 13y ago
  It used to be that almost all PC games were single threaded. Many still are: Civilization 4, Dwarf Fortress, and Morrowind, for example.

fulafel 13y ago

Many things are hard to parallelize using current technology, and there indeed has been lots of research done on it. History goes back to the supercomputer era (Cray, Connection Machine, Transputer etc.) The term of art is "inherently sequential" problems (vs "embarrassingly parallel"). In addition, the programming effort gets untenable quickly due to Amdahl's law when the amount of parallelism increases. Eg. if you have 100 cores, even if only 1% of work in your program is sequential, your performance goes down the drain. Currently we're in the comfy phase of the curve with few cores... We've been making good progress with parallel-minded reimaginings of programming languages and computer architectures on one front: GPUs. On the CPU we are saddled with the inertia and backwards compatibiltiy lock-in of tools and culture (witness lasting use of C++ as a tool to write parallel software)