From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Eric Dumazet <edumazet@google.com>,
Neal Cardwell <ncardwell@google.com>,
Yuchung Cheng <ycheng@google.com>,
"David S. Miller" <davem@davemloft.net>
Subject: [ 07/23] tcp: cubic: fix bug in bictcp_acked()
Date: Thu, 12 Sep 2013 10:45:03 -0700 [thread overview]
Message-ID: <20130912174452.567115745@linuxfoundation.org> (raw)
In-Reply-To: <20130912174451.748805761@linuxfoundation.org>
3.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@google.com>
[ Upstream commit cd6b423afd3c08b27e1fed52db828ade0addbc6b ]
While investigating about strange increase of retransmit rates
on hosts ~24 days after boot, Van found hystart was disabled
if ca->epoch_start was 0, as following condition is true
when tcp_time_stamp high order bit is set.
(s32)(tcp_time_stamp - ca->epoch_start) < HZ
Quoting Van :
At initialization & after every loss ca->epoch_start is set to zero so
I believe that the above line will turn off hystart as soon as the 2^31
bit is set in tcp_time_stamp & hystart will stay off for 24 days.
I think we've observed that cubic's restart is too aggressive without
hystart so this might account for the higher drop rate we observe.
Diagnosed-by: Van Jacobson <vanj@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/tcp_cubic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/ipv4/tcp_cubic.c
+++ b/net/ipv4/tcp_cubic.c
@@ -416,7 +416,7 @@ static void bictcp_acked(struct sock *sk
return;
/* Discard delay samples right after fast recovery */
- if ((s32)(tcp_time_stamp - ca->epoch_start) < HZ)
+ if (ca->epoch_start && (s32)(tcp_time_stamp - ca->epoch_start) < HZ)
return;
delay = (rtt_us << 3) / USEC_PER_MSEC;
next prev parent reply other threads:[~2013-09-12 17:45 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-12 17:44 [ 00/23] 3.4.62-stable review Greg Kroah-Hartman
2013-09-12 17:44 ` [ 01/23] htb: fix sign extension bug Greg Kroah-Hartman
2013-09-13 5:04 ` [00/23] 3.4.62-stable review Guenter Roeck
2013-09-13 12:35 ` Greg Kroah-Hartman
2013-09-12 17:44 ` [ 02/23] net: check net.core.somaxconn sysctl values Greg Kroah-Hartman
2013-09-12 17:44 ` [ 03/23] neighbour: populate neigh_parms on alloc before calling ndo_neigh_setup Greg Kroah-Hartman
2013-09-12 17:45 ` [ 04/23] bonding: modify only neigh_parms owned by us Greg Kroah-Hartman
2013-09-12 17:45 ` [ 05/23] fib_trie: remove potential out of bound access Greg Kroah-Hartman
2013-09-12 17:45 ` [ 06/23] tcp: cubic: fix overflow error in bictcp_update() Greg Kroah-Hartman
2013-09-12 17:45 ` Greg Kroah-Hartman [this message]
2013-09-12 17:45 ` [ 08/23] ipv6: dont stop backtracking in fib6_lookup_1 if subtree does not match Greg Kroah-Hartman
2013-09-12 17:45 ` [ 09/23] 8139cp: Fix skb leak in rx_status_loop failure path Greg Kroah-Hartman
2013-09-12 17:45 ` [ 10/23] tun: signedness bug in tun_get_user() Greg Kroah-Hartman
2013-09-12 17:45 ` [ 11/23] ipv6: remove max_addresses check from ipv6_create_tempaddr Greg Kroah-Hartman
2013-09-12 17:45 ` [ 12/23] ipv6: drop packets with multiple fragmentation headers Greg Kroah-Hartman
2013-09-12 17:45 ` [ 13/23] ipv6: Dont depend on per socket memory for neighbour discovery messages Greg Kroah-Hartman
2013-09-12 17:45 ` [ 14/23] net: bridge: convert MLDv2 Query MRC into msecs_to_jiffies for max_delay Greg Kroah-Hartman
2013-09-12 17:45 ` [ 15/23] ICMPv6: treat dest unreachable codes 5 and 6 as EACCES, not EPROTO Greg Kroah-Hartman
2013-09-12 17:45 ` [ 16/23] net: ipv6: tcp: fix potential use after free in tcp_v6_do_rcv Greg Kroah-Hartman
2013-09-12 17:45 ` [ 17/23] vhost: zerocopy: poll vq in zerocopy callback Greg Kroah-Hartman
2013-09-12 17:45 ` [ 18/23] macvtap: do not zerocopy if iov needs more pages than MAX_SKB_FRAGS Greg Kroah-Hartman
2013-09-12 17:45 ` [ 19/23] tipc: fix lockdep warning during bearer initialization Greg Kroah-Hartman
2013-09-12 17:45 ` [ 20/23] m32r: consistently use "suffix-$(...)" Greg Kroah-Hartman
2013-09-12 17:45 ` [ 21/23] m32r: add memcpy() for CONFIG_KERNEL_GZIP=y Greg Kroah-Hartman
2013-09-12 17:45 ` [ 22/23] m32r: make memset() global for CONFIG_KERNEL_BZIP2=y Greg Kroah-Hartman
2013-09-12 17:45 ` [ 23/23] Revert "KVM: X86 emulator: fix source operand decoding for 8bit mov[zs]x instructions" Greg Kroah-Hartman
2013-09-13 23:02 ` [ 00/23] 3.4.62-stable review Shuah Khan
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