On 02/06/2016 06:57 PM, Dave Chinner wrote:
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.
I have just sent out a new patchset using per-cpu list with per-cpu
locks. I used the per-cpu list as the changes will be simpler and easier
to review. Please let me know your thought on that.
Thanks,
Longman
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