Messages in this thread | | | Date | Wed, 6 Apr 2016 20:15:29 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2 2/2] rtmutex: Kill pi_waiters_leftmost from task_struct |
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On Wed, Apr 06, 2016 at 08:59:16PM +0800, Xunlei Pang wrote: > Current code use pi_waiters_leftmost to record the leftmost waiter, > but actually it can be get directly from task_struct::pi_waiters > using rb_first(). The performance penalty introduced by rb_first() > should be fine, because normally there aren't that many rtmutexes > chained together for one task. > > We don't remove rt_mutex:pi_waiters_leftmost, as it is quite possible > for many tasks sharing one rtmutex. > > Thus, hereby remove pi_waiters_leftmost from task_struct.
Again, I would like Thomas to chime in. This isn't about usual, but very much about worst case performance -- its RT code after all.
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