Re: [RFC PATCH] Add split_lock

2021-04-09 Thread Thomas Gleixner
On Thu, Apr 08 2021 at 12:18, Peter Zijlstra wrote: > On Thu, Apr 08, 2021 at 06:23:38AM +0100, Matthew Wilcox (Oracle) wrote: >> bit_spinlocks are horrible on RT because there's absolutely nowhere >> to put the mutex to sleep on. They also do not participate in lockdep >> because there's nowhere

Re: [RFC PATCH] Add split_lock

2021-04-08 Thread Peter Zijlstra
On Thu, Apr 08, 2021 at 06:23:38AM +0100, Matthew Wilcox (Oracle) wrote: > bit_spinlocks are horrible on RT because there's absolutely nowhere > to put the mutex to sleep on. They also do not participate in lockdep > because there's nowhere to put the map. > > Most (all?) bit spinlocks are

[RFC PATCH] Add split_lock

2021-04-07 Thread Matthew Wilcox (Oracle)
bit_spinlocks are horrible on RT because there's absolutely nowhere to put the mutex to sleep on. They also do not participate in lockdep because there's nowhere to put the map. Most (all?) bit spinlocks are actually a split lock; logically they could be treated as a single spinlock, but for