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-rw-r--r--target/linux/generic/backport-4.9/025-tcp-allow-drivers-to-tweak-TSQ-logic.patch85
1 files changed, 85 insertions, 0 deletions
diff --git a/target/linux/generic/backport-4.9/025-tcp-allow-drivers-to-tweak-TSQ-logic.patch b/target/linux/generic/backport-4.9/025-tcp-allow-drivers-to-tweak-TSQ-logic.patch
new file mode 100644
index 0000000000..446730ed16
--- /dev/null
+++ b/target/linux/generic/backport-4.9/025-tcp-allow-drivers-to-tweak-TSQ-logic.patch
@@ -0,0 +1,85 @@
+From: Eric Dumazet <edumazet@google.com>
+Date: Sat, 11 Nov 2017 15:54:12 -0800
+Subject: [PATCH] tcp: allow drivers to tweak TSQ logic
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+I had many reports that TSQ logic breaks wifi aggregation.
+
+Current logic is to allow up to 1 ms of bytes to be queued into qdisc
+and drivers queues.
+
+But Wifi aggregation needs a bigger budget to allow bigger rates to
+be discovered by various TCP Congestion Controls algorithms.
+
+This patch adds an extra socket field, allowing wifi drivers to select
+another log scale to derive TCP Small Queue credit from current pacing
+rate.
+
+Initial value is 10, meaning that this patch does not change current
+behavior.
+
+We expect wifi drivers to set this field to smaller values (tests have
+been done with values from 6 to 9)
+
+They would have to use following template :
+
+if (skb->sk && skb->sk->sk_pacing_shift != MY_PACING_SHIFT)
+ skb->sk->sk_pacing_shift = MY_PACING_SHIFT;
+
+Ref: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1670041
+Signed-off-by: Eric Dumazet <edumazet@google.com>
+Cc: Johannes Berg <johannes.berg@intel.com>
+Cc: Toke Høiland-Jørgensen <toke@toke.dk>
+Cc: Kir Kolyshkin <kir@openvz.org>
+---
+--- a/include/net/sock.h
++++ b/include/net/sock.h
+@@ -260,6 +260,7 @@ struct sock_common {
+ * @sk_gso_type: GSO type (e.g. %SKB_GSO_TCPV4)
+ * @sk_gso_max_size: Maximum GSO segment size to build
+ * @sk_gso_max_segs: Maximum number of GSO segments
++ * @sk_pacing_shift: scaling factor for TCP Small Queues
+ * @sk_lingertime: %SO_LINGER l_linger setting
+ * @sk_backlog: always used with the per-socket spinlock held
+ * @sk_callback_lock: used with the callbacks in the end of this struct
+@@ -421,6 +422,8 @@ struct sock {
+ kmemcheck_bitfield_end(flags);
+
+ u16 sk_gso_max_segs;
++#define sk_pacing_shift sk_pacing_shift /* for backport checks */
++ u8 sk_pacing_shift;
+ unsigned long sk_lingertime;
+ struct proto *sk_prot_creator;
+ rwlock_t sk_callback_lock;
+--- a/net/core/sock.c
++++ b/net/core/sock.c
+@@ -2478,6 +2478,7 @@ void sock_init_data(struct socket *sock,
+
+ sk->sk_max_pacing_rate = ~0U;
+ sk->sk_pacing_rate = ~0U;
++ sk->sk_pacing_shift = 10;
+ sk->sk_incoming_cpu = -1;
+ /*
+ * Before updating sk_refcnt, we must commit prior changes to memory
+--- a/net/ipv4/tcp_output.c
++++ b/net/ipv4/tcp_output.c
+@@ -1581,7 +1581,7 @@ u32 tcp_tso_autosize(const struct sock *
+ {
+ u32 bytes, segs;
+
+- bytes = min(sk->sk_pacing_rate >> 10,
++ bytes = min(sk->sk_pacing_rate >> sk->sk_pacing_shift,
+ sk->sk_gso_max_size - 1 - MAX_TCP_HEADER);
+
+ /* Goal is to send at least one packet per ms,
+@@ -2083,7 +2083,7 @@ static bool tcp_small_queue_check(struct
+ {
+ unsigned int limit;
+
+- limit = max(2 * skb->truesize, sk->sk_pacing_rate >> 10);
++ limit = max(2 * skb->truesize, sk->sk_pacing_rate >> sk->sk_pacing_shift);
+ limit = min_t(u32, limit, sysctl_tcp_limit_output_bytes);
+ limit <<= factor;
+