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vmscan: add shrink_slab tracepoints 

It is impossible to understand what the shrinkers are actually doing
without instrumenting the code, so add a some tracepoints to allow
insight to be gained.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Dave Chinner 2011-07-08 14:14:34 +10:00 committed by Al Viro
parent a9049376ee
commit 095760730c
2 changed files with 84 additions and 1 deletions
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77
include/trace/events/vmscan.h
View File

@ -179,6 +179,83 @@ DEFINE_EVENT(mm_vmscan_direct_reclaim_end_template, mm_vmscan_memcg_softlimit_re
TP_ARGS(nr_reclaimed)
);
TRACE_EVENT(mm_shrink_slab_start,
TP_PROTO(struct shrinker *shr, struct shrink_control *sc,
long nr_objects_to_shrink, unsigned long pgs_scanned,
unsigned long lru_pgs, unsigned long cache_items,
unsigned long long delta, unsigned long total_scan),
TP_ARGS(shr, sc, nr_objects_to_shrink, pgs_scanned, lru_pgs,
cache_items, delta, total_scan),
TP_STRUCT__entry(
__field(struct shrinker *, shr)
__field(void *, shrink)
__field(long, nr_objects_to_shrink)
__field(gfp_t, gfp_flags)
__field(unsigned long, pgs_scanned)
__field(unsigned long, lru_pgs)
__field(unsigned long, cache_items)
__field(unsigned long long, delta)
__field(unsigned long, total_scan)
),
TP_fast_assign(
__entry->shr = shr;
__entry->shrink = shr->shrink;
__entry->nr_objects_to_shrink = nr_objects_to_shrink;
__entry->gfp_flags = sc->gfp_mask;
__entry->pgs_scanned = pgs_scanned;
__entry->lru_pgs = lru_pgs;
__entry->cache_items = cache_items;
__entry->delta = delta;
__entry->total_scan = total_scan;
),
TP_printk("%pF %p: objects to shrink %ld gfp_flags %s pgs_scanned %ld lru_pgs %ld cache items %ld delta %lld total_scan %ld",
__entry->shrink,
__entry->shr,
__entry->nr_objects_to_shrink,
show_gfp_flags(__entry->gfp_flags),
__entry->pgs_scanned,
__entry->lru_pgs,
__entry->cache_items,
__entry->delta,
__entry->total_scan)
);
TRACE_EVENT(mm_shrink_slab_end,
TP_PROTO(struct shrinker *shr, int shrinker_retval,
long unused_scan_cnt, long new_scan_cnt),
TP_ARGS(shr, shrinker_retval, unused_scan_cnt, new_scan_cnt),
TP_STRUCT__entry(
__field(struct shrinker *, shr)
__field(void *, shrink)
__field(long, unused_scan)
__field(long, new_scan)
__field(int, retval)
__field(long, total_scan)
),
TP_fast_assign(
__entry->shr = shr;
__entry->shrink = shr->shrink;
__entry->unused_scan = unused_scan_cnt;
__entry->new_scan = new_scan_cnt;
__entry->retval = shrinker_retval;
__entry->total_scan = new_scan_cnt - unused_scan_cnt;
),
TP_printk("%pF %p: unused scan count %ld new scan count %ld total_scan %ld last shrinker return val %d",
__entry->shrink,
__entry->shr,
__entry->unused_scan,
__entry->new_scan,
__entry->total_scan,
__entry->retval)
);
DECLARE_EVENT_CLASS(mm_vmscan_lru_isolate_template,

8
mm/vmscan.c
View File

@ -250,6 +250,7 @@ unsigned long shrink_slab(struct shrink_control *shrink,
unsigned long long delta;
unsigned long total_scan;
unsigned long max_pass;
int shrink_ret = 0;
max_pass = do_shrinker_shrink(shrinker, shrink, 0);
delta = (4 * nr_pages_scanned) / shrinker->seeks;
@ -274,9 +275,12 @@ unsigned long shrink_slab(struct shrink_control *shrink,
total_scan = shrinker->nr;
shrinker->nr = 0;
trace_mm_shrink_slab_start(shrinker, shrink, total_scan,
nr_pages_scanned, lru_pages,
max_pass, delta, total_scan);
while (total_scan >= SHRINK_BATCH) {
long this_scan = SHRINK_BATCH;
int shrink_ret;
int nr_before;
nr_before = do_shrinker_shrink(shrinker, shrink, 0);
@ -293,6 +297,8 @@ unsigned long shrink_slab(struct shrink_control *shrink,
}
shrinker->nr += total_scan;
trace_mm_shrink_slab_end(shrinker, shrink_ret, total_scan,
shrinker->nr);
}
up_read(&shrinker_rwsem);
out: