Re: [PATCH] mm: Cleanup - Reorganize the shrink_page_list code into smaller functions

[Minchan Kim <minchan@kernel.org>]

On Tue, Jun 07, 2016 at 01:43:29PM -0700, Tim Chen wrote:
> On Tue, 2016-06-07 at 17:21 +0900, Minchan Kim wrote:
> > On Wed, Jun 01, 2016 at 11:23:53AM -0700, Tim Chen wrote:
> > > 
> > > On Wed, 2016-06-01 at 16:12 +0900, Minchan Kim wrote:
> > > > 
> > > >  
> > > > Hi Tim,
> > > > 
> > > > To me, this reorganization is too limited and not good for me,
> > > > frankly speaking. It works for only your goal which allocate batch
> > > > swap slot, I guess. :)
> > > > 
> > > > My goal is to make them work with batch page_check_references,
> > > > batch try_to_unmap and batch __remove_mapping where we can avoid frequent
> > > > mapping->lock(e.g., anon_vma or i_mmap_lock with hoping such batch locking
> > > > help system performance) if batch pages has same inode or anon.
> > > This is also my goal to group pages that are either under the same
> > > mapping or are anonymous pages together so we can reduce the i_mmap_lock
> > > acquisition.  One logic that's yet to be implemented in your patch
> > > is the grouping of similar pages together so we only need one i_mmap_lock
> > > acquisition.  Doing this efficiently is non-trivial.  
> > Hmm, my assumption is based on same inode pages are likely to order
> > in LRU so no need to group them. If successive page in page_list comes
> > from different inode, we can drop the lock and get new lock from new
> > inode. That sounds strange?
> > 
> 
> Sounds reasonable. But your process function passed to spl_batch_pages may
> need to be modified to know if the radix tree lock or swap info lock
> has already been held, as it deals with only 1 page.  It may be
> tricky as the lock may get acquired and dropped more than once in process
> function.
> 
> Are you planning to update the patch with lock batching?

Hi Tim,

Okay, I will give it a shot.

Thanks.

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