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Subject[PATCH 01/12] vmscan: add shrink_slab tracepoints
Date
From: Dave Chinner <dchinner@redhat.com>

Іt 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>
---
include/trace/events/vmscan.h | 67 +++++++++++++++++++++++++++++++++++++++++
mm/vmscan.c | 6 +++-
2 files changed, 72 insertions(+), 1 deletions(-)
diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
index ea422aa..c798cd7 100644
--- a/include/trace/events/vmscan.h
+++ b/include/trace/events/vmscan.h
@@ -310,6 +310,73 @@ TRACE_EVENT(mm_vmscan_lru_shrink_inactive,
show_reclaim_flags(__entry->reclaim_flags))
);

+TRACE_EVENT(mm_shrink_slab_start,
+ TP_PROTO(struct shrinker *shr, struct shrink_control *sc,
+ unsigned long pgs_scanned, unsigned long lru_pgs,
+ unsigned long cache_items, unsigned long long delta,
+ unsigned long total_scan),
+
+ TP_ARGS(shr, sc, pgs_scanned, lru_pgs, cache_items, delta, total_scan),
+
+ TP_STRUCT__entry(
+ __field(struct shrinker *, shr)
+ __field(long, shr_nr)
+ __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->shr_nr = shr->nr;
+ __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("shrinker %p: nr %ld gfp_flags %s pgs_scanned %ld lru_pgs %ld cache items %ld delta %lld total_scan %ld",
+ __entry->shr,
+ __entry->shr_nr,
+ 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_ret,
+ unsigned long total_scan),
+
+ TP_ARGS(shr, shrinker_ret, total_scan),
+
+ TP_STRUCT__entry(
+ __field(struct shrinker *, shr)
+ __field(long, shr_nr)
+ __field(int, shrinker_ret)
+ __field(unsigned long, total_scan)
+ ),
+
+ TP_fast_assign(
+ __entry->shr = shr;
+ __entry->shr_nr = shr->nr;
+ __entry->shrinker_ret = shrinker_ret;
+ __entry->total_scan = total_scan;
+ ),
+
+ TP_printk("shrinker %p: nr %ld total_scan %ld return val %d",
+ __entry->shr,
+ __entry->shr_nr,
+ __entry->total_scan,
+ __entry->shrinker_ret)
+);

#endif /* _TRACE_VMSCAN_H */

diff --git a/mm/vmscan.c b/mm/vmscan.c
index faa0a08..48e3fbd 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -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 +275,11 @@ unsigned long shrink_slab(struct shrink_control *shrink,
total_scan = shrinker->nr;
shrinker->nr = 0;

+ trace_mm_shrink_slab_start(shrinker, shrink, 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 +296,7 @@ unsigned long shrink_slab(struct shrink_control *shrink,
}

shrinker->nr += total_scan;
+ trace_mm_shrink_slab_end(shrinker, shrink_ret, total_scan);
}
up_read(&shrinker_rwsem);
out:
--
1.7.5.1
--
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