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

[Peter Zijlstra]

On Fri, Sep 16, 2016 at 03:25:06PM +0200, Peter Zijlstra wrote:
> 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.

https://www.kernel.org/doc/ols/2007/ols2007v2-pages-311-318.pdf