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Message-ID: <20150109085855.GC2110@esperanza>
Date: Fri, 9 Jan 2015 11:58:55 +0300
From: Vladimir Davydov <vdavydov@...allels.com>
To: Hillf Danton <hillf.zj@...baba-inc.com>
CC: Andrew Morton <akpm@...ux-foundation.org>,
'Johannes Weiner' <hannes@...xchg.org>,
'Michal Hocko' <mhocko@...e.cz>,
'Greg Thelen' <gthelen@...gle.com>,
'Glauber Costa' <glommer@...il.com>,
'Dave Chinner' <david@...morbit.com>,
'Alexander Viro' <viro@...iv.linux.org.uk>,
linux-kernel <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>
Subject: Re: [PATCH -mm v3 3/9] vmscan: per memory cgroup slab shrinkers
On Fri, Jan 09, 2015 at 02:33:46PM +0800, Hillf Danton wrote:
> > @@ -2318,16 +2357,22 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc,
> >
> > memcg = mem_cgroup_iter(root, NULL, &reclaim);
> > do {
> > - unsigned long lru_pages;
> > + unsigned long lru_pages, scanned;
> > struct lruvec *lruvec;
> > int swappiness;
> >
> > lruvec = mem_cgroup_zone_lruvec(zone, memcg);
> > swappiness = mem_cgroup_swappiness(memcg);
> > + scanned = sc->nr_scanned;
> >
> > shrink_lruvec(lruvec, swappiness, sc, &lru_pages);
> > zone_lru_pages += lru_pages;
> >
> > + if (memcg && is_classzone)
> > + shrink_slab(sc->gfp_mask, zone_to_nid(zone),
> > + memcg, sc->nr_scanned - scanned,
> > + lru_pages);
> > +
> Looks sc->nr_reclaimed has to be updated for "limit reclaim".
>
That's true, thank you for catching this!
I think we should move reclaim_state handling to shrink_slab(), as this
incremental patch does:
---
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 16f3e45742d6..6961bf0a47af 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -347,6 +347,7 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
* @memcg: memory cgroup whose slab caches to target
* @nr_scanned: pressure numerator
* @nr_eligible: pressure denominator
+ * @nr_reclaimed: number of reclaimed slab pages
*
* Call the shrink functions to age shrinkable caches.
*
@@ -372,8 +373,10 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
struct mem_cgroup *memcg,
unsigned long nr_scanned,
- unsigned long nr_eligible)
+ unsigned long nr_eligible,
+ unsigned long *nr_reclaimed)
{
+ struct reclaim_state *reclaim_state = current->reclaim_state;
struct shrinker *shrinker;
unsigned long freed = 0;
@@ -394,6 +397,9 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
goto out;
}
+ if (reclaim_state)
+ reclaim_state->reclaimed_slab = 0;
+
list_for_each_entry(shrinker, &shrinker_list, list) {
struct shrink_control sc = {
.gfp_mask = gfp_mask,
@@ -410,6 +416,9 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
freed += do_shrink_slab(&sc, shrinker, nr_scanned, nr_eligible);
}
+ if (reclaim_state)
+ *nr_reclaimed += reclaim_state->reclaimed_slab;
+
up_read(&shrinker_rwsem);
out:
cond_resched();
@@ -419,6 +428,7 @@ out:
void drop_slab_node(int nid)
{
unsigned long freed;
+ unsigned long nr_reclaimed = 0;
do {
struct mem_cgroup *memcg = NULL;
@@ -426,7 +436,7 @@ void drop_slab_node(int nid)
freed = 0;
do {
freed += shrink_slab(GFP_KERNEL, nid, memcg,
- 1000, 1000);
+ 1000, 1000, &nr_reclaimed);
} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
} while (freed > 10);
}
@@ -2339,7 +2349,6 @@ static inline bool should_continue_reclaim(struct zone *zone,
static bool shrink_zone(struct zone *zone, struct scan_control *sc,
bool is_classzone)
{
- struct reclaim_state *reclaim_state = current->reclaim_state;
unsigned long nr_reclaimed, nr_scanned;
bool reclaimable = false;
@@ -2371,7 +2380,7 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc,
if (memcg && is_classzone)
shrink_slab(sc->gfp_mask, zone_to_nid(zone),
memcg, sc->nr_scanned - scanned,
- lru_pages);
+ lru_pages, &sc->nr_reclaimed);
/*
* Direct reclaim and kswapd have to scan all memory
@@ -2398,12 +2407,7 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc,
if (global_reclaim(sc) && is_classzone)
shrink_slab(sc->gfp_mask, zone_to_nid(zone), NULL,
sc->nr_scanned - nr_scanned,
- zone_lru_pages);
-
- if (reclaim_state) {
- sc->nr_reclaimed += reclaim_state->reclaimed_slab;
- reclaim_state->reclaimed_slab = 0;
- }
+ zone_lru_pages, &sc->nr_reclaimed);
vmpressure(sc->gfp_mask, sc->target_mem_cgroup,
sc->nr_scanned - nr_scanned,
@@ -3367,10 +3371,7 @@ static int kswapd(void *p)
int balanced_classzone_idx;
pg_data_t *pgdat = (pg_data_t*)p;
struct task_struct *tsk = current;
-
- struct reclaim_state reclaim_state = {
- .reclaimed_slab = 0,
- };
+ struct reclaim_state reclaim_state;
const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
lockdep_set_current_reclaim_state(GFP_KERNEL);
@@ -3508,7 +3509,6 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
p->flags |= PF_MEMALLOC;
lockdep_set_current_reclaim_state(sc.gfp_mask);
- reclaim_state.reclaimed_slab = 0;
p->reclaim_state = &reclaim_state;
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
@@ -3697,7 +3697,6 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
*/
p->flags |= PF_MEMALLOC | PF_SWAPWRITE;
lockdep_set_current_reclaim_state(gfp_mask);
- reclaim_state.reclaimed_slab = 0;
p->reclaim_state = &reclaim_state;
if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) {
--
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