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authorJesper Dangaard Brouer <brouer@redhat.com>2019-04-12 17:07:32 +0200
committerAlexei Starovoitov <ast@kernel.org>2019-04-17 19:09:24 -0700
commit77361825bb01ecadf3ac8622e2e4dbc28806e858 (patch)
treec521a9c061e9cc31281cc613cb9ed7b11e517286 /kernel/bpf
parent00967e84f742f87603e769529628e32076ade188 (diff)
downloadlinux-77361825bb01ecadf3ac8622e2e4dbc28806e858.tar.bz2
bpf: cpumap use ptr_ring_consume_batched
Move ptr_ring dequeue outside loop, that allocate SKBs and calls network stack, as these operations that can take some time. The ptr_ring is a communication channel between CPUs, where we want to reduce/limit any cacheline bouncing. Do a concentrated bulk dequeue via ptr_ring_consume_batched, to shorten the period and times the remote cacheline in ptr_ring is read Batch size 8 is both to (1) limit BH-disable period, and (2) consume one cacheline on 64-bit archs. After reducing the BH-disable section further then we can consider changing this, while still thinking about L1 cacheline size being active. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/cpumap.c21
1 files changed, 11 insertions, 10 deletions
diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index 3c18260403dd..430103e182a0 100644
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -240,6 +240,8 @@ static void put_cpu_map_entry(struct bpf_cpu_map_entry *rcpu)
}
}
+#define CPUMAP_BATCH 8
+
static int cpu_map_kthread_run(void *data)
{
struct bpf_cpu_map_entry *rcpu = data;
@@ -252,8 +254,9 @@ static int cpu_map_kthread_run(void *data)
* kthread_stop signal until queue is empty.
*/
while (!kthread_should_stop() || !__ptr_ring_empty(rcpu->queue)) {
- unsigned int processed = 0, drops = 0, sched = 0;
- struct xdp_frame *xdpf;
+ unsigned int drops = 0, sched = 0;
+ void *frames[CPUMAP_BATCH];
+ int i, n;
/* Release CPU reschedule checks */
if (__ptr_ring_empty(rcpu->queue)) {
@@ -269,14 +272,16 @@ static int cpu_map_kthread_run(void *data)
sched = cond_resched();
}
- /* Process packets in rcpu->queue */
- local_bh_disable();
/*
* The bpf_cpu_map_entry is single consumer, with this
* kthread CPU pinned. Lockless access to ptr_ring
* consume side valid as no-resize allowed of queue.
*/
- while ((xdpf = __ptr_ring_consume(rcpu->queue))) {
+ n = ptr_ring_consume_batched(rcpu->queue, frames, CPUMAP_BATCH);
+
+ local_bh_disable();
+ for (i = 0; i < n; i++) {
+ struct xdp_frame *xdpf = frames[i];
struct sk_buff *skb;
int ret;
@@ -290,13 +295,9 @@ static int cpu_map_kthread_run(void *data)
ret = netif_receive_skb_core(skb);
if (ret == NET_RX_DROP)
drops++;
-
- /* Limit BH-disable period */
- if (++processed == 8)
- break;
}
/* Feedback loop via tracepoint */
- trace_xdp_cpumap_kthread(rcpu->map_id, processed, drops, sched);
+ trace_xdp_cpumap_kthread(rcpu->map_id, n, drops, sched);
local_bh_enable(); /* resched point, may call do_softirq() */
}