net: introduce SO_MAX_PACING_RATE
As mentioned in commit afe4fd062416b ("pkt_sched: fq: Fair Queue packet
scheduler"), this patch adds a new socket option.
SO_MAX_PACING_RATE offers the application the ability to cap the
rate computed by transport layer. Value is in bytes per second.
u32 val = 1000000;
setsockopt(sockfd, SOL_SOCKET, SO_MAX_PACING_RATE, &val, sizeof(val));
To be effectively paced, a flow must use FQ packet scheduler.
Note that a packet scheduler takes into account the headers for its
computations. The effective payload rate depends on MSS and retransmits
if any.
I chose to make this pacing rate a SOL_SOCKET option instead of a
TCP one because this can be used by other protocols.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Steinar H. Gunderson <sesse@google.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/sock.c b/net/core/sock.c
index 5b6beba..2bd9b3f 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -914,6 +914,13 @@
}
break;
#endif
+
+ case SO_MAX_PACING_RATE:
+ sk->sk_max_pacing_rate = val;
+ sk->sk_pacing_rate = min(sk->sk_pacing_rate,
+ sk->sk_max_pacing_rate);
+ break;
+
default:
ret = -ENOPROTOOPT;
break;
@@ -1177,6 +1184,10 @@
break;
#endif
+ case SO_MAX_PACING_RATE:
+ v.val = sk->sk_max_pacing_rate;
+ break;
+
default:
return -ENOPROTOOPT;
}
@@ -2319,6 +2330,7 @@
sk->sk_ll_usec = sysctl_net_busy_read;
#endif
+ sk->sk_max_pacing_rate = ~0U;
/*
* Before updating sk_refcnt, we must commit prior changes to memory
* (Documentation/RCU/rculist_nulls.txt for details)