Replace PSQ timer queue with a timer wheel #84
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* fibers/timer-wheel.scm: New file. * Makefile.am (SOURCES): Add to build.
* fibers/scheduler.scm (<scheduler>): A scheduler's timers is no longer a functional priority queue, but rather a timer wheel. This should decrease overhead. There is one open question about ordering within a tick; you create a wheel with a particular precision, and it will choose a precision at least that precise (and no more than twice as precise). Within a tick, however, events are unordered. Does it matter? We can add a sort phase here, perhaps when inserting the events.
Now that sleeping is cheaper, we can have more parallel sleepers.
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HI! I just read the article (very nice!) and kind of followed the implementation. This is great. Please, merge! |
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packaging changes: NetBSD fixes are now upstream fibers 1.3.1 -- 2023-05-30 ========================== * Fix posix-clocks-darwin usage of extension library. fibers 1.3.0 -- 2023-05-29 ========================== * Replace PSQ timer queue with new timer wheel. (see wingo/fibers#84) * Fix libevent cross-compilation issues. * Always define (getaffinity) and (setaffinity) if not found. * Rename 'scm_pipe2' to 'scm_fibers_pipe2' to fix a build error with Guile 3.0.9. * Fix bit-vector deprecation warnings.
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This PR adds a timer wheel, like https://www.snellman.net/blog/archive/2016-07-27-ratas-hierarchical-timer-wheel/. I ported it from https://github.com/snabbco/snabb/blob/master/src/lib/fibers/timer.lua, which I also wrote. It seems to increase the number of threads that can
(sleep 1)concurrently by about a factor of 15 or so. WDYT @aconchillo ?