From: Dave Chinner <dchinner@xxxxxxxxxx> commit 095760730c1047c69159ce88021a7fa3833502c8 upstream. Stable note: This patch makes later patches easier to apply but otherwise has little to justify it. It is a diagnostic patch that was part of a series addressing excessive slab shrinking after GFP_NOFS failures. There is detailed information on the series' motivation at https://lkml.org/lkml/2011/6/2/42 . 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@xxxxxxxxxx> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Signed-off-by: Mel Gorman <mgorman@xxxxxxx> --- include/trace/events/vmscan.h | 77 +++++++++++++++++++++++++++++++++++++++++ mm/vmscan.c | 8 ++++- 2 files changed, 84 insertions(+), 1 deletion(-) diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h index b2c33bd..36851f7 100644 --- a/include/trace/events/vmscan.h +++ b/include/trace/events/vmscan.h @@ -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, diff --git a/mm/vmscan.c b/mm/vmscan.c index 72340b84..d875058 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 +275,12 @@ 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: -- 1.7.9.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>