Small smr_grace_wait() optimization

Make the SMR thread maintain an explicit system-wide grace period and
make CPUs observe the current grace period when crossing a quiescent
state. This lets the SMR thread avoid a forced context switch for CPUs
that have already entered the latest grace period.

This change provides a small improvement in smr_grace_wait()'s
performance in terms of context switching.

OK mpi@, anton@

0 files changed, 0 insertions, 0 deletions