CoroutineScheduler: do not re-add stolen task to the head of the WorkerQueue where the task can be stolen from again #3416
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qwwdfsad
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Nov 22, 2022
It solves two problems: * Stealing into exclusively owned local queue does no longer require and CAS'es or atomic operations where they were previously not needed. It should save a few cycles on the stealing code path * The overall timing perturbations should be slightly better now: previously it was possible for the stolen task to be immediately got stolen again from the stealer thread because it was actually published to owner's queue, but its submission time was never updated Fixes #3416
qwwdfsad
added a commit
that referenced
this issue
Nov 22, 2022
It solves two problems: * Stealing into exclusively owned local queue does no longer require and CAS'es or atomic operations where they were previously not needed. It should save a few cycles on the stealing code path * The overall timing perturbations should be slightly better now: previously it was possible for the stolen task to be immediately got stolen again from the stealer thread because it was actually published to owner's queue, but its submission time was never updated Fixes #3416
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We should hand it directly to the stealing worker without intermediate stores.
Apart from code being more straightforward, it also saves us at least 2 CASes on a fairly contended memory location
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