On 02/15/2019 01:40 PM, Will Deacon wrote: > On Thu, Feb 14, 2019 at 11:37:15AM +0100, Peter Zijlstra wrote: >> On Wed, Feb 13, 2019 at 05:00:14PM -0500, Waiman Long wrote: >>> v4: >>> - Remove rwsem-spinlock.c and make all archs use rwsem-xadd.c. >>> >>> v3: >>> - Optimize __down_read_trylock() for the uncontended case as suggested >>> by Linus. >>> >>> v2: >>> - Add patch 2 to optimize __down_read_trylock() as suggested by PeterZ. >>> - Update performance test data in patch 1. >>> >>> The goal of this patchset is to remove the architecture specific files >>> for rwsem-xadd to make it easer to add enhancements in the later rwsem >>> patches. It also removes the legacy rwsem-spinlock.c file and make all >>> the architectures use one single implementation of rwsem - rwsem-xadd.c. >>> >>> Waiman Long (3): >>> locking/rwsem: Remove arch specific rwsem files >>> locking/rwsem: Remove rwsem-spinlock.c & use rwsem-xadd.c for all >>> archs >>> locking/rwsem: Optimize down_read_trylock() >> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> >> >> with the caveat that I'm happy to exchange patch 3 back to my earlier >> suggestion in case Will expesses concerns wrt the ARM64 performance of >> Linus' suggestion. > Right, the current proposal doesn't work well for us, unfortunately. Which > was your earlier suggestion? > > Will In my posting yesterday, I showed that most of the trylocks done were actually uncontended. Assuming that pattern hold for the most of the workloads, it will not that bad after all. -Longman
