Roll forward: "Detect when the kernel multiplexed hw counters." #2423
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Even though we now pin counters, tests show that multiplexing
is still happening.
NEW: Fixes the original commit to use tmp_attr properly for the
case of
IN_TXCP
.This reverts commit 3677e44.
Our use case:
A host is running linux perf now and then to get machine stats, in parallel to
rr
.Without this detection, rr silently succeeds.