Re: [PATCH] mm: unmapped page migration avoid unmap+remap overhead

2014-11-30 Thread Yasuaki Ishimatsu
(2014/12/01 16:28), Hugh Dickins wrote: On Mon, 1 Dec 2014, Yasuaki Ishimatsu wrote: (2014/12/01 13:52), Hugh Dickins wrote: @@ -798,7 +798,7 @@ static int __unmap_and_move(struct page int force, enum migrate_mode mode) { int rc = -EAGAIN; - int

Re: [PATCH] mm: unmapped page migration avoid unmap+remap overhead

2014-11-30 Thread Hugh Dickins
On Mon, 1 Dec 2014, Yasuaki Ishimatsu wrote: > (2014/12/01 13:52), Hugh Dickins wrote: > > @@ -798,7 +798,7 @@ static int __unmap_and_move(struct page > > int force, enum migrate_mode mode) > > { > > int rc = -EAGAIN; > > - int remap_swapcache = 1; > > + int pa

Re: [PATCH] mm: unmapped page migration avoid unmap+remap overhead

2014-11-30 Thread Yasuaki Ishimatsu
(2014/12/01 13:52), Hugh Dickins wrote: Page migration's __unmap_and_move(), and rmap's try_to_unmap(), were created for use on pages almost certainly mapped into userspace. But nowadays compaction often applies them to unmapped page cache pages: which may exacerbate contention on i_mmap_rwsem qu

[PATCH] mm: unmapped page migration avoid unmap+remap overhead

2014-11-30 Thread Hugh Dickins
Page migration's __unmap_and_move(), and rmap's try_to_unmap(), were created for use on pages almost certainly mapped into userspace. But nowadays compaction often applies them to unmapped page cache pages: which may exacerbate contention on i_mmap_rwsem quite unnecessarily, since try_to_unmap_file