Messages in this thread | | | Date | Tue, 07 Oct 2008 10:23:22 -0500 | From | Christoph Lameter <> | Subject | Re: [PATCH 3/3] Convert the UDP hash lock to RCU |
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Eric Dumazet wrote:
> > 1) Hum, do you know why "struct file" objects dont use > SLAB_DESTROY_BY_RCU then, > since we noticed a performance regression for several workloads at > RCUification > of file structures ?
Because my patches were not accepted that fix the issue. http://lkml.org/lkml/2006/6/16/144
> 2) What prevents an object to be *freed* (and deleted from a hash > chain), then > re-allocated and inserted to another chain (different keys) ? (final > refcount=1)
Nothing.
> If the lookup detects a key mismatch, how will it continue to the next > item, > since 'next' pointer will have been reused for the new chain insertion... > > Me confused...
If there is a mismatch then you have to do another hash lookup. Do an rcu unlock and start over.
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