Messages in this thread | | | Date | Sun, 7 Feb 2016 10:57:44 +1100 | From | Dave Chinner <> | Subject | Re: [PATCH v2 1/3] lib/list_batch: A simple list insertion/deletion batching facility |
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On Wed, Feb 03, 2016 at 06:11:56PM -0500, Waiman Long wrote: > On 01/31/2016 07:47 PM, Dave Chinner wrote: > >So at what point does simply replacing the list_head with a list_lru > >become more efficient than this batch processing (i.e. > >https://lkml.org/lkml/2015/3/10/660)? The list_lru isn't a great > >fit for the inode list (doesn't need any of the special LRU/memcg > >stuff https://lkml.org/lkml/2015/3/16/261) but it will tell us if, > >like Ingo suggested, moving more towards a generic per-cpu list > >would provide better overall performance... > > I will take a look at the list_lru patch to see if that help. As for > the per-cpu list, I tried that and it didn't quite work out.
OK, see my last email as to why Andi's patch didn't change anything. The list_lru implementation has a list per node, a lock per node, and each item is placed on the list for the node it is physically allocated from. Hence for local workloads, the list/lock that is accessed for add/remove should be local to the node and hence should reduce cache line contention mostly to within a single node.
Cheers,
Dave. -- Dave Chinner david@fromorbit.com
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