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72 lines
2.2 KiB
Diff
72 lines
2.2 KiB
Diff
From b223feb9de2a65c533ff95c08e834fa732906ea5 Mon Sep 17 00:00:00 2001
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From: Eric Dumazet <edumazet@google.com>
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Date: Sat, 3 Dec 2016 11:14:52 -0800
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Subject: [PATCH 03/10] tcp: tsq: add shortcut in tcp_tasklet_func()
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Under high stress, I've seen tcp_tasklet_func() consuming
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~700 usec, handling ~150 tcp sockets.
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By setting TCP_TSQ_DEFERRED in tcp_wfree(), we give a chance
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for other cpus/threads entering tcp_write_xmit() to grab it,
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allowing tcp_tasklet_func() to skip sockets that already did
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an xmit cycle.
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In the future, we might give to ACK processing an increased
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budget to reduce even more tcp_tasklet_func() amount of work.
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Signed-off-by: Eric Dumazet <edumazet@google.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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net/ipv4/tcp_output.c | 22 ++++++++++++----------
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1 file changed, 12 insertions(+), 10 deletions(-)
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--- a/net/ipv4/tcp_output.c
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+++ b/net/ipv4/tcp_output.c
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@@ -767,19 +767,19 @@ static void tcp_tasklet_func(unsigned lo
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list_for_each_safe(q, n, &list) {
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tp = list_entry(q, struct tcp_sock, tsq_node);
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list_del(&tp->tsq_node);
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+ clear_bit(TSQ_QUEUED, &tp->tsq_flags);
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sk = (struct sock *)tp;
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- bh_lock_sock(sk);
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-
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- if (!sock_owned_by_user(sk)) {
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- tcp_tsq_handler(sk);
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- } else {
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- /* defer the work to tcp_release_cb() */
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- set_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags);
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+ if (!sk->sk_lock.owned &&
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+ test_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags)) {
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+ bh_lock_sock(sk);
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+ if (!sock_owned_by_user(sk)) {
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+ clear_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags);
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+ tcp_tsq_handler(sk);
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+ }
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+ bh_unlock_sock(sk);
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}
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- bh_unlock_sock(sk);
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- clear_bit(TSQ_QUEUED, &tp->tsq_flags);
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sk_free(sk);
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}
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}
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@@ -884,7 +884,7 @@ void tcp_wfree(struct sk_buff *skb)
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if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED))
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goto out;
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- nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED;
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+ nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED | TCPF_TSQ_DEFERRED;
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nval = cmpxchg(&tp->tsq_flags, oval, nval);
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if (nval != oval)
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continue;
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@@ -2183,6 +2183,8 @@ static bool tcp_write_xmit(struct sock *
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unlikely(tso_fragment(sk, skb, limit, mss_now, gfp)))
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break;
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+ if (test_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags))
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+ clear_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags);
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if (tcp_small_queue_check(sk, skb, 0))
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break;
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