linux-stable/net
Eric Dumazet b49960a05e tcp: change tcp_adv_win_scale and tcp_rmem[2]
tcp_adv_win_scale default value is 2, meaning we expect a good citizen
skb to have skb->len / skb->truesize ratio of 75% (3/4)

In 2.6 kernels we (mis)accounted for typical MSS=1460 frame :
1536 + 64 + 256 = 1856 'estimated truesize', and 1856 * 3/4 = 1392.
So these skbs were considered as not bloated.

With recent truesize fixes, a typical MSS=1460 frame truesize is now the
more precise :
2048 + 256 = 2304. But 2304 * 3/4 = 1728.
So these skb are not good citizen anymore, because 1460 < 1728

(GRO can escape this problem because it build skbs with a too low
truesize.)

This also means tcp advertises a too optimistic window for a given
allocated rcvspace : When receiving frames, sk_rmem_alloc can hit
sk_rcvbuf limit and we call tcp_prune_queue()/tcp_collapse() too often,
especially when application is slow to drain its receive queue or in
case of losses (netperf is fast, scp is slow). This is a major latency
source.

We should adjust the len/truesize ratio to 50% instead of 75%

This patch :

1) changes tcp_adv_win_scale default to 1 instead of 2

2) increase tcp_rmem[2] limit from 4MB to 6MB to take into account
better truesize tracking and to allow autotuning tcp receive window to
reach same value than before. Note that same amount of kernel memory is
consumed compared to 2.6 kernels.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-05-02 21:08:58 -04:00
..
9p net/9p: handle flushed Tclunk/Tremove 2012-02-26 14:49:57 -06:00
802 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-04-02 17:53:39 -07:00
8021q
appletalk
atm Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
ax25 net ax25: Reorder ax25_exit to remove races. 2012-04-19 15:37:48 -04:00
batman-adv Merge tag 'batman-adv-for-davem' of git://git.open-mesh.org/linux-merge 2012-03-11 15:36:34 -07:00
bluetooth Merge branch 'for-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth 2012-04-27 15:16:43 -04:00
bridge set fake_rtable's dst to NULL to avoid kernel Oops 2012-04-24 00:16:24 -04:00
caif caif: Fix memory leakage in the chnl_net.c. 2012-04-13 11:01:44 -04:00
can
ceph libceph: isolate kmap() call in write_partial_msg_pages() 2012-03-22 10:47:52 -05:00
core drop_monitor: prevent init path from scheduling on the wrong cpu 2012-05-02 21:02:48 -04:00
dcb
dccp dccp: fix bug in sequence number validation during connection setup 2012-03-03 09:02:52 -07:00
decnet Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
dns_resolver
dsa
econet Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
ethernet Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
ieee802154 6lowpan: add missing spin_lock_init() 2012-04-26 05:32:55 -04:00
ipv4 tcp: change tcp_adv_win_scale and tcp_rmem[2] 2012-05-02 21:08:58 -04:00
ipv6 tcp: fix TCP_MAXSEG for established IPv6 passive sockets 2012-04-22 17:09:35 -04:00
ipx
irda Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
iucv Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2012-03-22 18:15:32 -07:00
key net/key/af_key.c: add missing kfree_skb 2012-04-13 11:01:44 -04:00
l2tp net: l2tp: unlock socket lock before returning from l2tp_ip_sendmsg 2012-05-02 21:04:33 -04:00
lapb Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
llc
mac80211 mac80211: fix AP mode EAP tx for VLAN stations 2012-04-30 14:40:05 -04:00
netfilter netfilter: xt_CT: fix wrong checking in the timeout assignment path 2012-04-30 10:40:36 +02:00
netlabel netlabel: use GFP flags from caller instead of GFP_ATOMIC 2012-03-22 19:29:57 -04:00
netlink netlink: fix races after skb queueing 2012-04-06 04:21:06 -04:00
netrom Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
nfc NFC: Fix the LLCP Tx fragmentation loop 2012-04-11 15:09:33 -04:00
openvswitch Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
packet Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
phonet phonet: Sort out initiailziation and cleanup code. 2012-04-13 11:01:43 -04:00
rds RDS: use gfp flags from caller in conn_alloc() 2012-03-22 19:29:58 -04:00
rfkill device.h: cleanup users outside of linux/include (C files) 2012-03-11 14:27:37 -04:00
rose Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-04-02 17:53:39 -07:00
rxrpc
sched netem: fix possible skb leak 2012-05-01 13:40:48 -04:00
sctp sctp: Allow struct sctp_event_subscribe to grow without breaking binaries 2012-04-04 18:05:02 -04:00
sunrpc Merge branch 'for-3.4' of git://linux-nfs.org/~bfields/linux 2012-03-29 14:53:25 -07:00
tipc tipc: Optimize setting of immutable payload message header fields 2012-02-29 11:45:35 -05:00
unix poll: add poll_requested_events() and poll_does_not_wait() functions 2012-03-23 16:58:38 -07:00
wanrouter
wimax
wireless cfg80211: fix interface combinations check. 2012-04-13 14:05:35 -04:00
x25
xfrm xfrm: Access the replay notify functions via the registered callbacks 2012-03-22 19:29:58 -04:00
compat.c Merge branch 'x86-x32-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-29 18:12:23 -07:00
Kconfig
Makefile
nonet.c
socket.c tcp: tcp_sendpages() should call tcp_push() once 2012-04-05 19:04:27 -04:00
sysctl_net.c