Restartable sequences
Restartable sequences
Posted Jul 15, 2015 18:42 UTC (Wed) by nix (subscriber, #2304)In reply to: Restartable sequences by dgm
Parent article: Restartable sequences
I thought the whole point of using futexes for locks in NPTL was so that no syscalls were necessary for them in the uncontended case, either, in which case this whole thing is no faster than the locky approach (but is a lot more complex).
Posted Jul 15, 2015 19:54 UTC (Wed)
by Cyberax (✭ supporter ✭, #52523)
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Restartable sequences
Futexes have to use atomic operations for their fastpaths and they are quite slow. You can't avoid them because your thread might be migrated to another CPU, so non-atomic memory access will likely ruin everything.