IB/hfi1: Add unique txwait_lock for txreq events
Profiling suggests that the read_seqbegin() in the txreq put logic is colliding with other uses of the iowait lock. The packet at a time use of this lock dictates a unique lock to avoid reader/writer collisions when the number of vTxWait events is low. In order to support a unique lock the iowait struct embedded in the QP is extended to remember the lock that protects the queue head. The QP destroy removes that QP from any wait list. It doesn't need to know the head because of the linked list API, but it does need to know the lock required to protect the head. This also opens up the wait logic to have unique per resources locks which needs to be in future refinement. Reviewed-by: Sebastian Sanchez <sebastian.sanchez@intel.com> Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
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