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Miller" , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , Jamal Hadi Salim , Jiri Pirko , netdev@vger.kernel.org, eric.dumazet@gmail.com, Eric Dumazet Content-Type: text/plain; charset="UTF-8" Using kmem_cache_free_bulk() in fq_gc() was not optimal. 1) It needs an array. 2) It is only saving cpu cycles for large batches. The automatic array forces a stack canary, which is expensive. In practive fq_gc was finding zero, one or two flows at most per round. Remove the array, use kmem_cache_free(). This makes fq_enqueue() smaller and faster. $ scripts/bloat-o-meter -t vmlinux.old vmlinux.new add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-79 (-79) Function old new delta fq_enqueue 1629 1550 -79 Total: Before=24886583, After=24886504, chg -0.00% Signed-off-by: Eric Dumazet --- net/sched/sch_fq.c | 24 +++++++++++------------- 1 file changed, 11 insertions(+), 13 deletions(-) diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c index d0200ec8ada62e86f10d823556bedcaefb470e6c..80235e85f8440ee83032f171cf28df6f161473db 100644 --- a/net/sched/sch_fq.c +++ b/net/sched/sch_fq.c @@ -245,8 +245,6 @@ static void fq_flow_set_throttled(struct fq_sched_data *q, struct fq_flow *f) static struct kmem_cache *fq_flow_cachep __read_mostly; -/* limit number of collected flows per round */ -#define FQ_GC_MAX 8 #define FQ_GC_AGE (3*HZ) static bool fq_gc_candidate(const struct fq_flow *f) @@ -259,10 +257,9 @@ static void fq_gc(struct fq_sched_data *q, struct rb_root *root, struct sock *sk) { + struct fq_flow *f, *tofree = NULL; struct rb_node **p, *parent; - void *tofree[FQ_GC_MAX]; - struct fq_flow *f; - int i, fcnt = 0; + int fcnt; p = &root->rb_node; parent = NULL; @@ -274,9 +271,8 @@ static void fq_gc(struct fq_sched_data *q, break; if (fq_gc_candidate(f)) { - tofree[fcnt++] = f; - if (fcnt == FQ_GC_MAX) - break; + f->next = tofree; + tofree = f; } if (f->sk > sk) @@ -285,18 +281,20 @@ static void fq_gc(struct fq_sched_data *q, p = &parent->rb_left; } - if (!fcnt) + if (!tofree) return; - for (i = fcnt; i > 0; ) { - f = tofree[--i]; + fcnt = 0; + while (tofree) { + f = tofree; + tofree = f->next; rb_erase(&f->fq_node, root); + kmem_cache_free(fq_flow_cachep, f); + fcnt++; } q->flows -= fcnt; q->inactive_flows -= fcnt; q->stat_gc_flows += fcnt; - - kmem_cache_free_bulk(fq_flow_cachep, fcnt, tofree); } /* Fast path can be used if : -- 2.53.0.rc2.204.g2597b5adb4-goog