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net: call skb_defer_free_flush() from __napi_busy_loop()

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skb_defer_free_flush() is currently called from net_rx_action()
and napi_threaded_poll().

We should also call it from __napi_busy_loop() otherwise
there is the risk the percpu queue can grow until an IPI
is forced from skb_attempt_defer_free() adding a latency spike.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20240227210105.3815474-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-02-27 21:01:04 +00:00 committed by Jakub Kicinski
parent 9912362205
commit 1200097fa8
1 changed files with 22 additions and 21 deletions
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43
net/core/dev.c
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@ -6173,6 +6173,27 @@ struct napi_struct *napi_by_id(unsigned int napi_id)
return NULL;
}
static void skb_defer_free_flush(struct softnet_data *sd)
{
struct sk_buff *skb, *next;
/* Paired with WRITE_ONCE() in skb_attempt_defer_free() */
if (!READ_ONCE(sd->defer_list))
return;
spin_lock(&sd->defer_lock);
skb = sd->defer_list;
sd->defer_list = NULL;
sd->defer_count = 0;
spin_unlock(&sd->defer_lock);
while (skb != NULL) {
next = skb->next;
napi_consume_skb(skb, 1);
skb = next;
}
}
#if defined(CONFIG_NET_RX_BUSY_POLL)
static void __busy_poll_stop(struct napi_struct *napi, bool skip_schedule)
@ -6297,6 +6318,7 @@ count:
if (work > 0)
__NET_ADD_STATS(dev_net(napi->dev),
LINUX_MIB_BUSYPOLLRXPACKETS, work);
skb_defer_free_flush(this_cpu_ptr(&softnet_data));
local_bh_enable();
if (!loop_end || loop_end(loop_end_arg, start_time))
@ -6726,27 +6748,6 @@ static int napi_thread_wait(struct napi_struct *napi)
return -1;
}
static void skb_defer_free_flush(struct softnet_data *sd)
{
struct sk_buff *skb, *next;
/* Paired with WRITE_ONCE() in skb_attempt_defer_free() */
if (!READ_ONCE(sd->defer_list))
return;
spin_lock(&sd->defer_lock);
skb = sd->defer_list;
sd->defer_list = NULL;
sd->defer_count = 0;
spin_unlock(&sd->defer_lock);
while (skb != NULL) {
next = skb->next;
napi_consume_skb(skb, 1);
skb = next;
}
}
static int napi_threaded_poll(void *data)
{
struct napi_struct *napi = data;