Messages in this thread | | | Date | Fri, 22 Aug 2008 12:14:37 -0500 | From | Christoph Lameter <> | Subject | Re: [PATCH 2/2] smp_call_function: use rwlocks on queues rather than rcu |
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Paul E. McKenney wrote:
>> RCU is problematic because it lets cachelines get cold. A hot cacheline that >> is used frequently read and written to by the same cpu is very good thing for >> performace. > > So on your these large boxes, read-only cachelines are preferentially > ejected from the cache, so that one should write to per-CPU data > occasionally to keep it resident? Or is the issue the long RCU grace > periods which allow the structure being freed to age out of all relevant > caches? (My guess would be the second.)
The issue are the RCU grace period that are generally long enough to make the cacheline fall out of all caches.
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