From c9f1f58dc2eba550f208809d272bf0b14f41edba Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Tue, 12 Dec 2017 06:34:19 -0800
Subject: [PATCH] net: sk_pacing_shift_update() helper
In commit 3a9b76fd0db9 ("tcp: allow drivers to tweak TSQ logic")
I gave a code sample to set sk->sk_pacing_shift that was not complete.
Better add a helper that can be used by drivers without worries,
and maybe amended in the future.
A wifi driver might use it from its ndo_start_xmit()
Following call would setup TCP to allow up to ~8ms of queued data per
flow.
sk_pacing_shift_update(skb->sk, 7);
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/net/sock.h | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/include/net/sock.h b/include/net/sock.h
index 9155da422692..9a9047268d37 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2407,4 +2407,15 @@ static inline int sk_get_rmem0(const struct sock *sk, const struct proto *proto)
return *proto->sysctl_rmem;
}
+/* Default TCP Small queue budget is ~1 ms of data (1sec >> 10)
+ * Some wifi drivers need to tweak it to get more chunks.
+ * They can use this helper from their ndo_start_xmit()
+ */
+static inline void sk_pacing_shift_update(struct sock *sk, int val)
+{
+ if (!sk || !sk_fullsock(sk) || sk->sk_pacing_shift == val)
+ return;
+ sk->sk_pacing_shift = val;
+}
+
#endif /* _SOCK_H */
--
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