opal/timer: add code to check if rtdtsc is core invariant #2596
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Newer x86 processors have a core invariant tsc. On these systems it is safe to use the rtdtsc instruction as a monotonic timer. This commit adds a new function to the opal timer code to check if the timer backend is monotonic. On x86 it checks the appropriate bit and on other architectures it parrots back the OPAL_TIMER_MONOTONIC value. Signed-off-by: Nathan Hjelm <[email protected]>
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@hjelmn have you tested this on KNL? |
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bot:lanl:retest |
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@hppritcha Haven't tested this on KNL yet. Being a newer processor I would hope the invariant tsc is available. BTW, I now I have reports back from 3 code teams. They all report getting the same or better performance as 1.6.5 on TLCC2 systems when using the tsc timer. CTS-1 systems show a similar speedup. |
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Newer x86 processors have a core invariant tsc. On these systems it is
safe to use the rtdtsc instruction as a monotonic timer. This commit
adds a new function to the opal timer code to check if the timer
backend is monotonic. On x86 it checks the appropriate bit and on
other architectures it parrots back the OPAL_TIMER_MONOTONIC value.
Signed-off-by: Nathan Hjelm [email protected]