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| author | Soheil Hassas Yeganeh <soheil@google.com> | 2020-09-14 17:52:09 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-30 12:42:07 +0100 |
| commit | 7e120db7306fd338aba2eb11e0baf88e0f12de68 (patch) | |
| tree | 95e85f5482761a02df9ba1b846f9e7689d9542d6 /net | |
| parent | 0d70e638abbfc91b15eaf2699610d16f00b4cdd8 (diff) | |
| download | linux-stable-7e120db7306fd338aba2eb11e0baf88e0f12de68.tar.gz linux-stable-7e120db7306fd338aba2eb11e0baf88e0f12de68.tar.bz2 linux-stable-7e120db7306fd338aba2eb11e0baf88e0f12de68.zip | |
tcp: return EPOLLOUT from tcp_poll only when notsent_bytes is half the limit
[ Upstream commit 8ba3c9d1c6d75d1e6af2087278b30e17f68e1fff ]
If there was any event available on the TCP socket, tcp_poll()
will be called to retrieve all the events. In tcp_poll(), we call
sk_stream_is_writeable() which returns true as long as we are at least
one byte below notsent_lowat. This will result in quite a few
spurious EPLLOUT and frequent tiny sendmsg() calls as a result.
Similar to sk_stream_write_space(), use __sk_stream_is_writeable
with a wake value of 1, so that we set EPOLLOUT only if half the
space is available for write.
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: e14cadfd80d7 ("tcp: add annotations around sk->sk_shutdown accesses")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 68f89fe7f923..2fcf6e5a371d 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -576,7 +576,7 @@ __poll_t tcp_poll(struct file *file, struct socket *sock, poll_table *wait) mask |= EPOLLIN | EPOLLRDNORM; if (!(sk->sk_shutdown & SEND_SHUTDOWN)) { - if (sk_stream_is_writeable(sk)) { + if (__sk_stream_is_writeable(sk, 1)) { mask |= EPOLLOUT | EPOLLWRNORM; } else { /* send SIGIO later */ sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); @@ -588,7 +588,7 @@ __poll_t tcp_poll(struct file *file, struct socket *sock, poll_table *wait) * pairs with the input side. */ smp_mb__after_atomic(); - if (sk_stream_is_writeable(sk)) + if (__sk_stream_is_writeable(sk, 1)) mask |= EPOLLOUT | EPOLLWRNORM; } } else |