On Tue, Oct 22, 2019 at 08:08:23PM +0000, Roman Gushchin wrote:
> On Tue, Oct 22, 2019 at 10:48:02AM -0400, Johannes Weiner wrote:
> > This function is getting long and unwieldy, split out the memcg bits.
> >
> > The updated shrink_node() handles the generic (node) reclaim aspects:
> > - global vmpressure notifications
> > - writeback and congestion throttling
> > - reclaim/compaction management
> > - kswapd giving up on unreclaimable nodes
> >
> > It then calls a new shrink_node_memcgs() which handles cgroup specifics:
> > - the cgroup tree traversal
> > - memory.low considerations
> > - per-cgroup slab shrinking callbacks
> > - per-cgroup vmpressure notifications
> >
> > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> > ---
> > mm/vmscan.c | 28 ++++++++++++++++++----------
> > 1 file changed, 18 insertions(+), 10 deletions(-)
> >
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index db073b40c432..65baa89740dd 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -2722,18 +2722,10 @@ static bool pgdat_memcg_congested(pg_data_t *pgdat, struct mem_cgroup *memcg)
> > (memcg && memcg_congested(pgdat, memcg));
> > }
> >
> > -static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
> > +static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
> > {
> > - struct reclaim_state *reclaim_state = current->reclaim_state;
> > struct mem_cgroup *root = sc->target_mem_cgroup;
> > - unsigned long nr_reclaimed, nr_scanned;
> > - bool reclaimable = false;
> > struct mem_cgroup *memcg;
> > -again:
> > - memset(&sc->nr, 0, sizeof(sc->nr));
> > -
> > - nr_reclaimed = sc->nr_reclaimed;
> > - nr_scanned = sc->nr_scanned;
> >
> > memcg = mem_cgroup_iter(root, NULL, NULL);
> > do {
> > @@ -2786,6 +2778,22 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
> > sc->nr_reclaimed - reclaimed);
> >
> > } while ((memcg = mem_cgroup_iter(root, memcg, NULL)));
> > +}
> > +
> > +static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
> > +{
> > + struct reclaim_state *reclaim_state = current->reclaim_state;
> > + struct mem_cgroup *root = sc->target_mem_cgroup;
> > + unsigned long nr_reclaimed, nr_scanned;
> > + bool reclaimable = false;
> > +
> > +again:
> > + memset(&sc->nr, 0, sizeof(sc->nr));
> > +
> > + nr_reclaimed = sc->nr_reclaimed;
> > + nr_scanned = sc->nr_scanned;
> > +
> > + shrink_node_memcgs(pgdat, sc);
> >
> > if (reclaim_state) {
> > sc->nr_reclaimed += reclaim_state->reclaimed_slab;
> > @@ -2793,7 +2801,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
> > }
> >
> > /* Record the subtree's reclaim efficiency */
> > - vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true,
> > + vmpressure(sc->gfp_mask, root, true,
>
> Maybe target? Or target_memcg? The word root is associated with the root cgroup.
>
> Other than root the patch looks good to me:
>
> Reviewed-by: Roman Gushchin <guro@xxxxxx>
Thanks!
I agree, target_memcg is better than root. The next patch also
replaces some of these with target_lruvec.
This on top?
>From f981c99d3a9da05513c5137873315974782e97ec Mon Sep 17 00:00:00 2001
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Date: Fri, 25 Oct 2019 10:28:42 -0400
Subject: [PATCH] mm: vmscan: split shrink_node() into node part and
memcgs part fix
As per Roman's suggestion, rename "root" to "target_memcg" to avoid
confusion with the global cgroup root, root_mem_cgroup.
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
mm/vmscan.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 65baa89740dd..6199692af434 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2724,16 +2724,16 @@ static bool pgdat_memcg_congested(pg_data_t *pgdat, struct mem_cgroup *memcg)
static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
{
- struct mem_cgroup *root = sc->target_mem_cgroup;
+ struct mem_cgroup *target_memcg = sc->target_mem_cgroup;
struct mem_cgroup *memcg;
- memcg = mem_cgroup_iter(root, NULL, NULL);
+ memcg = mem_cgroup_iter(target_memcg, NULL, NULL);
do {
struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
unsigned long reclaimed;
unsigned long scanned;
- switch (mem_cgroup_protected(root, memcg)) {
+ switch (mem_cgroup_protected(target_memcg, memcg)) {
case MEMCG_PROT_MIN:
/*
* Hard protection.
@@ -2777,13 +2777,13 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
sc->nr_scanned - scanned,
sc->nr_reclaimed - reclaimed);
- } while ((memcg = mem_cgroup_iter(root, memcg, NULL)));
+ } while ((memcg = mem_cgroup_iter(target_memcg, memcg, NULL)));
}
static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
{
struct reclaim_state *reclaim_state = current->reclaim_state;
- struct mem_cgroup *root = sc->target_mem_cgroup;
+ struct mem_cgroup *target_memcg = sc->target_mem_cgroup;
unsigned long nr_reclaimed, nr_scanned;
bool reclaimable = false;
@@ -2801,7 +2801,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
}
/* Record the subtree's reclaim efficiency */
- vmpressure(sc->gfp_mask, root, true,
+ vmpressure(sc->gfp_mask, target_memcg, true,
sc->nr_scanned - nr_scanned,
sc->nr_reclaimed - nr_reclaimed);
@@ -2857,7 +2857,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
*/
if (cgroup_reclaim(sc) && writeback_throttling_sane(sc) &&
sc->nr.dirty && sc->nr.dirty == sc->nr.congested)
- set_memcg_congestion(pgdat, root, true);
+ set_memcg_congestion(pgdat, target_memcg, true);
/*
* Stall direct reclaim for IO completions if underlying BDIs
@@ -2866,7 +2866,8 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
* the LRU too quickly.
*/
if (!sc->hibernation_mode && !current_is_kswapd() &&
- current_may_throttle() && pgdat_memcg_congested(pgdat, root))
+ current_may_throttle() &&
+ pgdat_memcg_congested(pgdat, target_memcg))
wait_iff_congested(BLK_RW_ASYNC, HZ/10);
if (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed,
--
2.23.0
