On Wed, 2017-03-08 at 15:26 +0800, Huang, Ying wrote: > From: Huang Ying <[email protected]> > > The swap cluster allocation/free functions are added based on the > existing swap cluster management mechanism for SSD. These functions > don't work for the rotating hard disks because the existing swap cluster > management mechanism doesn't work for them. The hard disks support may > be added if someone really need it. But that needn't be included in > this patchset. > > This will be used for the THP (Transparent Huge Page) swap support. > Where one swap cluster will hold the contents of each THP swapped out. > > Cc: Andrea Arcangeli <[email protected]> > Cc: Kirill A. Shutemov <[email protected]> > Cc: Hugh Dickins <[email protected]> > Cc: Shaohua Li <[email protected]> > Cc: Minchan Kim <[email protected]> > Cc: Rik van Riel <[email protected]> > Signed-off-by: "Huang, Ying" <[email protected]> > --- > mm/swapfile.c | 217 > +++++++++++++++++++++++++++++++++++++++++----------------- > 1 file changed, 156 insertions(+), 61 deletions(-) > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index a744604384ff..91876c33114b 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -378,6 +378,14 @@ static void swap_cluster_schedule_discard(struct > swap_info_struct *si, > schedule_work(&si->discard_work); > } > > +static void __free_cluster(struct swap_info_struct *si, unsigned long idx) > +{ > + struct swap_cluster_info *ci = si->cluster_info; > + > + cluster_set_flag(ci + idx, CLUSTER_FLAG_FREE); > + cluster_list_add_tail(&si->free_clusters, ci, idx); > +} > + > /* > * Doing discard actually. After a cluster discard is finished, the cluster > * will be added to free cluster list. caller should hold si->lock. > @@ -398,10 +406,7 @@ static void swap_do_scheduled_discard(struct > swap_info_struct *si) > > spin_lock(&si->lock); > ci = lock_cluster(si, idx * SWAPFILE_CLUSTER); > - cluster_set_flag(ci, CLUSTER_FLAG_FREE); > - unlock_cluster(ci); > - cluster_list_add_tail(&si->free_clusters, info, idx); > - ci = lock_cluster(si, idx * SWAPFILE_CLUSTER); > + __free_cluster(si, idx); > memset(si->swap_map + idx * SWAPFILE_CLUSTER, > 0, SWAPFILE_CLUSTER); > unlock_cluster(ci);
The __free_cluster definition and the above change to eliminate the extra unlock_cluster and lock_cluster can perhaps be broken up as a separate patch. It can be independent of THP changes. Tim
