Use busy waiting barrier in reduction to band #864
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This is high priority for performance in reduction to band, but on hold until the next pika release. |
rasolca
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msimberg
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msimberg
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I've added a config option to busy wait in the tridiagonal solver barriers as well but I have not yet tested if it has the same effect as in the reduction to band algorithm. |
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I rebased this and made the default busy wait time 0 for the rank 1 problem barrier. |
rasolca
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Jun 12, 2023
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Fixes #833, using the busy wait parameter to
barrier::waitin pika-org/pika#685. I've added configuration option for the busy wait time (in microseconds) specifically for reduction to band. #860 will probably also need to use the busy waiting barrier. We can see if we want to merge the options into a singleBARRIER_BUSY_WAIT_USoption, or if we need separateTRIDIAG_SOLVER_BARRIER_BUSY_WAIT_US,RED2BAND_BARRIER_BUSY_WAIT_USetc. The default value for the busy wait is 1 ms which seemed to show the best performance across daint and eiger, while still being relatively low (about the min task size that we anyway recommend).