Re: [PATCH 1/4] mm, vmscan: Batch removal of mappings under a single lock during reclaim

From: Peter Zijlstra
Date: Fri Sep 16 2016 - 09:25:58 EST

On Fri, Sep 09, 2016 at 10:59:32AM +0100, Mel Gorman wrote:
> Pages unmapped during reclaim acquire/release the mapping->tree_lock for
> every single page. There are two cases when it's likely that pages at the
> tail of the LRU share the same mapping -- large amounts of IO to/from a
> single file and swapping. This patch acquires the mapping->tree_lock for
> multiple page removals.

So, once upon a time, in a galaxy far away,.. I did a concurrent
pagecache patch set that replaced the tree_lock with a per page bit-
spinlock and fine grained locking in the radix tree.

I know the mm has changed quite a bit since, but would such an approach
still be feasible?

I cannot seem to find an online reference to a 'complete' version of
that patch set, but I did find the OLS paper on it and I did find some
copies on my local machines.