Messages in this thread Patch in this message | | | Date | Sat, 18 Apr 2009 20:43:37 +0200 | From | Johannes Weiner <> | Subject | Re: [PATCH for mmotm 0414] vmscan,memcg: reintroduce sc->may_swap |
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Hi KOSAKI-san,
On Sat, Apr 18, 2009 at 03:26:02PM +0900, KOSAKI Motohiro wrote: > Subject: vmscan,memcg: reintroduce sc->may_swap > > vmscan-rename-scmay_swap-to-may_unmap.patch removed may_swap flag, > but memcg had used it as a flag for "we need to use swap?", as the > name indicate. > > And in current implementation, memcg cannot reclaim mapped file caches > when mem+swap hits the limit. > > re-introduce may_swap flag and handle it at get_scan_ratio(). > This patch doesn't influence any scan_control users other than memcg. > > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> > Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> > -- > mm/vmscan.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > Index: b/mm/vmscan.c > =================================================================== > --- a/mm/vmscan.c 2009-04-16 21:25:41.000000000 +0900 > +++ b/mm/vmscan.c 2009-04-16 21:56:54.000000000 +0900 > @@ -64,6 +64,9 @@ struct scan_control { > /* Can mapped pages be reclaimed? */ > int may_unmap; > > + /* Can pages be swapped as part of reclaim? */ > + int may_swap; > + > /* This context's SWAP_CLUSTER_MAX. If freeing memory for > * suspend, we effectively ignore SWAP_CLUSTER_MAX. > * In this context, it doesn't matter that we scan the > @@ -1387,7 +1390,7 @@ static void get_scan_ratio(struct zone * > struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); > > /* If we have no swap space, do not bother scanning anon pages. */ > - if (nr_swap_pages <= 0) { > + if (!sc->may_swap || (nr_swap_pages <= 0)) {
I wonder if may_swap is a good name for this effect. See below the __zone_reclaim() comments.
> percent[0] = 0; > percent[1] = 100; > return; > @@ -1704,6 +1707,7 @@ unsigned long try_to_free_pages(struct z > .may_writepage = !laptop_mode, > .swap_cluster_max = SWAP_CLUSTER_MAX, > .may_unmap = 1, > + .may_swap = 1, > .swappiness = vm_swappiness, > .order = order, > .mem_cgroup = NULL, > @@ -1724,6 +1728,7 @@ unsigned long try_to_free_mem_cgroup_pag > struct scan_control sc = { > .may_writepage = !laptop_mode, > .may_unmap = 1, > + .may_swap = 1, > .swap_cluster_max = SWAP_CLUSTER_MAX, > .swappiness = swappiness, > .order = 0, > @@ -1734,7 +1739,7 @@ unsigned long try_to_free_mem_cgroup_pag > struct zonelist *zonelist; > > if (noswap) > - sc.may_unmap = 0; > + sc.may_swap = 0;
Can this be directly initialized?
struct scan_control sc = { ... .may_swap = !noswap, ... };
> sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | > (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); > @@ -1774,6 +1779,7 @@ static unsigned long balance_pgdat(pg_da > struct scan_control sc = { > .gfp_mask = GFP_KERNEL, > .may_unmap = 1, > + .may_swap = 1, > .swap_cluster_max = SWAP_CLUSTER_MAX, > .swappiness = vm_swappiness, > .order = order, > @@ -2120,6 +2126,7 @@ unsigned long shrink_all_memory(unsigned > struct scan_control sc = { > .gfp_mask = GFP_KERNEL, > .may_unmap = 0, > + .may_swap = 1,
shrink_all_memory() is not a user of shrink_zone() -> get_scan_ratio() and therefor not affected by this flag. I think it's better not to set it here (just like sc->swappiness).
> .may_writepage = 1, > .isolate_pages = isolate_pages_global, > }; > @@ -2304,6 +2311,7 @@ static int __zone_reclaim(struct zone *z > struct scan_control sc = { > .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), > .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP), > + .may_swap = 1,
Shouldn't this be set to !!(zone_reclaim_mode & RECLAIM_SWAP) as well?
With set to 1, zone_reclaim() will also reclaim unmapped swap cache pages (without swapping) and it might be desirable to do that. But then may_swap is a confusing name. may_anon? may_scan_anon? scan_anon?
Hannes
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