diff options
| author | Eric Dumazet | 2026-02-04 19:00:34 +0000 |
|---|---|---|
| committer | Jakub Kicinski | 2026-02-06 20:03:44 -0800 |
| commit | 2214aab26811c77a15fc1d28bf3112a07b8c8d85 (patch) | |
| tree | 62ad1a886237b9018d612f0c55c9539414bc45b7 /net | |
| parent | 7acee67a6bce02e0af8a4bf7b412e2164d5a48e9 (diff) | |
net_sched: sch_fq: rework fq_gc() to avoid stack canary
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 practice 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 <edumazet@google.com>
Link: https://patch.msgid.link/20260204190034.76277-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/sched/sch_fq.c | 24 |
1 files changed, 11 insertions, 13 deletions
diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c index d0200ec8ada6..80235e85f844 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 : |