On Fri, Jun 14, 2019 at 04:22:19PM -0700, Eric Dumazet wrote:
> Instead of relying on rps_needed, it is safer to use a separate
> static key, since we do not want to enable TCP rx_skb_cache
> by default. This feature can cause huge increase of memory
> usage on hosts with millions of sockets.
Thanks for the effort!
Acked-by: Feng Tang <feng.t...@intel.com>
>
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> ---
> Documentation/networking/ip-sysctl.txt | 8 ++++++++
> include/net/sock.h | 6 ++----
> net/ipv4/sysctl_net_ipv4.c | 9 +++++++++
> 3 files changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/networking/ip-sysctl.txt
> b/Documentation/networking/ip-sysctl.txt
> index
> 14fe93049d28e965d7349b03c5c8782c3d386e7d..288aa264ac26d98637a5bb1babc334bfc699bef1
> 100644
> --- a/Documentation/networking/ip-sysctl.txt
> +++ b/Documentation/networking/ip-sysctl.txt
> @@ -772,6 +772,14 @@ tcp_challenge_ack_limit - INTEGER
> in RFC 5961 (Improving TCP's Robustness to Blind In-Window Attacks)
> Default: 100
>
> +tcp_rx_skb_cache - BOOLEAN
> + Controls a per TCP socket cache of one skb, that might help
> + performance of some workloads. This might be dangerous
> + on systems with a lot of TCP sockets, since it increases
> + memory usage.
> +
> + Default: 0 (disabled)
> +
> UDP variables:
>
> udp_l3mdev_accept - BOOLEAN
> diff --git a/include/net/sock.h b/include/net/sock.h
> index
> e9d769c04637a3c0b967c9bfa6def724834796b9..b02645e2dfad722769c1455bcde76e46da9fc5ac
> 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -2433,13 +2433,11 @@ static inline void skb_setup_tx_timestamp(struct
> sk_buff *skb, __u16 tsflags)
> * This routine must be called with interrupts disabled or with the socket
> * locked so that the sk_buff queue operation is ok.
> */
> +DECLARE_STATIC_KEY_FALSE(tcp_rx_skb_cache_key);
> static inline void sk_eat_skb(struct sock *sk, struct sk_buff *skb)
> {
> __skb_unlink(skb, &sk->sk_receive_queue);
> - if (
> -#ifdef CONFIG_RPS
> - !static_branch_unlikely(&rps_needed) &&
> -#endif
> + if (static_branch_unlikely(&tcp_rx_skb_cache_key) &&
> !sk->sk_rx_skb_cache) {
> sk->sk_rx_skb_cache = skb;
> skb_orphan(skb);
> diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
> index
> 875867b64d6a6597bf4fcd3498ed55741cbe33f7..886b58d31351df44725bdc34081e798bcb89ecf0
> 100644
> --- a/net/ipv4/sysctl_net_ipv4.c
> +++ b/net/ipv4/sysctl_net_ipv4.c
> @@ -51,6 +51,9 @@ static int comp_sack_nr_max = 255;
> static u32 u32_max_div_HZ = UINT_MAX / HZ;
> static int one_day_secs = 24 * 3600;
>
> +DEFINE_STATIC_KEY_FALSE(tcp_rx_skb_cache_key);
> +EXPORT_SYMBOL(tcp_rx_skb_cache_key);
> +
> /* obsolete */
> static int sysctl_tcp_low_latency __read_mostly;
>
> @@ -559,6 +562,12 @@ static struct ctl_table ipv4_table[] = {
> .extra1 = &sysctl_fib_sync_mem_min,
> .extra2 = &sysctl_fib_sync_mem_max,
> },
> + {
> + .procname = "tcp_rx_skb_cache",
> + .data = &tcp_rx_skb_cache_key.key,
> + .mode = 0644,
> + .proc_handler = proc_do_static_key,
> + },
> { }
> };
>
> --
> 2.22.0.410.gd8fdbe21b5-goog
