Messages in this thread | | | Subject | Re: [PATCH v2] rwsem: Support optimistic spinning | From | Tim Chen <> | Date | Wed, 30 Apr 2014 14:28:05 -0700 |
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On Wed, 2014-04-30 at 14:06 -0700, Davidlohr Bueso wrote:
> > > > > > > > > > if (count == RWSEM_WAITING_BIAS) > > > > > old = cmpxchg(&sem->count, count, count + RWSEM_ACTIVE_BIAS); > > > > > else > > > > > old = cmpxchg(&sem->count, count, count + RWSEM_ACTIVE_WRITE_BIAS); > > > > > > > > I think I simply mis-typed it; shouldn't both cases be > > > > RWSEM_ACTIVE_WRITE_BIAS ? > > > > > > Yeah, we should just write it as > > > old = cmpxchg(&sem->count, count, RWSEM_ACTIVE_WRITE_BIAS); > > > > Oops, I mean > > old = cmpxchg(&sem->count, count, count + RWSEM_ACTIVE_WRITE_BIAS); > > > > for count == 0, we need sem->count to be RWSEM_ACTIVE_WRITE_BIAS, > > for count == RWSEM_WAITING_BIAS, we need sem->count to be RWSEM_WAITING_BIAS + RWSEM_ACTIVE_WRITE_BIAS > > Yep, I had just noticed this. Peter's original suggestion was correct, > just needed to change RWSEM_ACTIVE_BIAS for RWSEM_ACTIVE_WRITE_BIAS. >
Yes, I think we are all on the same page now.
Tim
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