Re: [patch 9/11] net: dst_entry.refcount, use, lastuse to use alloc_percpu

From: Ravikiran G Thirumalai
Date: Tue Sep 13 2005 - 17:08:16 EST


On Tue, Sep 13, 2005 at 01:24:42PM -0700, David S. Miller wrote:
>
> There is no way in the world this enormous amount of NUMA
> complexity is being added to the destination cache layer.

Agreed the dst changes are ugly; that can be worked on. But the
cacheline bouncing problem on the atomic_t dst_entry refcounter has been
around for quite a while -- even on SMPs, not just NUMA. We need a solution
for that. I thought you were against the dst_entry bloat caused by the
previous version of the dst patch. alloc_percpu takes that away. You had
concerns about workloads with low route locality. Unfortunately we don't have
access to infrastructure setup for such tests :(

As for the ugliness, would something on the lines of net_device refcounter
patch in the series above be acceptable?

Thanks,
Kiran
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