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85 lines
2.9 KiB
85 lines
2.9 KiB
From: Eric Dumazet <edumazet@google.com>
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Date: Sat, 11 Nov 2017 15:54:12 -0800
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Subject: [PATCH] tcp: allow drivers to tweak TSQ logic
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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I had many reports that TSQ logic breaks wifi aggregation.
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Current logic is to allow up to 1 ms of bytes to be queued into qdisc
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and drivers queues.
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But Wifi aggregation needs a bigger budget to allow bigger rates to
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be discovered by various TCP Congestion Controls algorithms.
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This patch adds an extra socket field, allowing wifi drivers to select
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another log scale to derive TCP Small Queue credit from current pacing
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rate.
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Initial value is 10, meaning that this patch does not change current
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behavior.
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We expect wifi drivers to set this field to smaller values (tests have
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been done with values from 6 to 9)
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They would have to use following template :
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if (skb->sk && skb->sk->sk_pacing_shift != MY_PACING_SHIFT)
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skb->sk->sk_pacing_shift = MY_PACING_SHIFT;
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Ref: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1670041
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Signed-off-by: Eric Dumazet <edumazet@google.com>
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Cc: Johannes Berg <johannes.berg@intel.com>
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Cc: Toke Høiland-Jørgensen <toke@toke.dk>
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Cc: Kir Kolyshkin <kir@openvz.org>
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---
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--- a/include/net/sock.h
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+++ b/include/net/sock.h
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@@ -267,6 +267,7 @@ struct sock_common {
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* @sk_gso_type: GSO type (e.g. %SKB_GSO_TCPV4)
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* @sk_gso_max_size: Maximum GSO segment size to build
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* @sk_gso_max_segs: Maximum number of GSO segments
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+ * @sk_pacing_shift: scaling factor for TCP Small Queues
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* @sk_lingertime: %SO_LINGER l_linger setting
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* @sk_backlog: always used with the per-socket spinlock held
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* @sk_callback_lock: used with the callbacks in the end of this struct
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@@ -446,6 +447,8 @@ struct sock {
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sk_type : 16;
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#define SK_PROTOCOL_MAX U8_MAX
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u16 sk_gso_max_segs;
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+#define sk_pacing_shift sk_pacing_shift /* for backport checks */
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+ u8 sk_pacing_shift;
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unsigned long sk_lingertime;
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struct proto *sk_prot_creator;
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rwlock_t sk_callback_lock;
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--- a/net/core/sock.c
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+++ b/net/core/sock.c
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@@ -2745,6 +2745,7 @@ void sock_init_data(struct socket *sock,
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sk->sk_max_pacing_rate = ~0U;
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sk->sk_pacing_rate = ~0U;
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+ sk->sk_pacing_shift = 10;
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sk->sk_incoming_cpu = -1;
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/*
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* Before updating sk_refcnt, we must commit prior changes to memory
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--- a/net/ipv4/tcp_output.c
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+++ b/net/ipv4/tcp_output.c
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@@ -1697,7 +1697,7 @@ u32 tcp_tso_autosize(const struct sock *
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{
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u32 bytes, segs;
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- bytes = min(sk->sk_pacing_rate >> 10,
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+ bytes = min(sk->sk_pacing_rate >> sk->sk_pacing_shift,
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sk->sk_gso_max_size - 1 - MAX_TCP_HEADER);
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/* Goal is to send at least one packet per ms,
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@@ -2215,7 +2215,7 @@ static bool tcp_small_queue_check(struct
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{
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unsigned int limit;
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- limit = max(2 * skb->truesize, sk->sk_pacing_rate >> 10);
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+ limit = max(2 * skb->truesize, sk->sk_pacing_rate >> sk->sk_pacing_shift);
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limit = min_t(u32, limit, sysctl_tcp_limit_output_bytes);
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limit <<= factor;
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