linux-toradex.git/net/ipv4/tcp.c, branch v3.0.29

net: refine {udp|tcp|sctp}_mem limits

2011-07-07T07:27:05+00:00

Current tcp/udp/sctp global memory limits are not taking into account
hugepages allocations, and allow 50% of ram to be used by buffers of a
single protocol [ not counting space used by sockets / inodes ...]

Lets use nr_free_buffer_pages() and allow a default of 1/8 of kernel ram
per protocol, and a minimum of 128 pages.
Heavy duty machines sysadmins probably need to tweak limits anyway.


References: https://bugzilla.stlinux.com/show_bug.cgi?id=38032
Reported-by: starlight 
Suggested-by: Andrew Morton 
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: Allow no-cache copy from user on transmit

2011-04-05T05:30:30+00:00

This patch uses __copy_from_user_nocache on transmit to bypass data
cache for a performance improvement.  skb_add_data_nocache and
skb_copy_to_page_nocache can be called by sendmsg functions to use
this feature, initial support is in tcp_sendmsg.  This functionality is
configurable per device using ethtool.

Presumably, this feature would only be useful when the driver does
not touch the data.  The feature is turned on by default if a device
indicates that it does some form of checksum offload; it is off by
default for devices that do no checksum offload or indicate no checksum
is necessary.  For the former case copy-checksum is probably done
anyway, in the latter case the device is likely loopback in which case
the no cache copy is probably not beneficial.

This patch was tested using 200 instances of netperf TCP_RR with
1400 byte request and one byte reply.  Platform is 16 core AMD x86.

No-cache copy disabled:
   672703 tps, 97.13% utilization
   50/90/99% latency:244.31 484.205 1028.41

No-cache copy enabled:
   702113 tps, 96.16% utilization,
   50/90/99% latency 238.56 467.56 956.955

Using 14000 byte request and response sizes demonstrate the
effects more dramatically:

No-cache copy disabled:
   79571 tps, 34.34 %utlization
   50/90/95% latency 1584.46 2319.59 5001.76

No-cache copy enabled:
   83856 tps, 34.81% utilization
   50/90/95% latency 2508.42 2622.62 2735.88

Note especially the effect on latency tail (95th percentile).

This seems to provide a nice performance improvement and is
consistent in the tests I ran.  Presumably, this would provide
the greatest benfits in the presence of an application workload
stressing the cache and a lot of transmit data happening.

Signed-off-by: Tom Herbert 
Signed-off-by: David S. Miller

tcp: ioctl type SIOCOUTQNSD returns amount of data not sent

2011-03-09T22:08:09+00:00

In contrast to SIOCOUTQ which returns the amount of data sent
but not yet acknowledged plus data not yet sent this patch only
returns the data not sent.

For various methods of live streaming bitrate control it may
be helpful to know how much data are in the tcp outqueue are
not sent yet.

Signed-off-by: Mario Schuknecht 
Signed-off-by: Steffen Sledz 
Signed-off-by: David S. Miller

tcp: Remove debug macro of TCP_CHECK_TIMER

2011-02-20T19:10:14+00:00

Now, TCP_CHECK_TIMER is not used for debuging, it does nothing.
And, it has been there for several years, maybe 6 years.

Remove it to keep code clearer.

Signed-off-by: Shan Wei 
Signed-off-by: David S. Miller

net: change netdev->features to u32

2011-01-24T23:32:47+00:00

Quoting Ben Hutchings: we presumably won't be defining features that
can only be enabled on 64-bit architectures.

Occurences found by `grep -r` on net/, drivers/net, include/

[ Move features and vlan_features next to each other in
  struct netdev, as per Eric Dumazet's suggestion -DaveM ]

Signed-off-by: Michał Mirosław 
Signed-off-by: David S. Miller

Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6

2010-12-08T21:47:38+00:00

Conflicts:
	drivers/net/wireless/ath/ath9k/ar9003_eeprom.c
	net/llc/af_llc.c

tcp: Make TCP_MAXSEG minimum more correct.

2010-11-24T19:47:22+00:00

Use TCP_MIN_MSS instead of constant 64.

Reported-by: Min Zhang 
Signed-off-by: David S. Miller

Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6

2010-11-14T19:57:05+00:00

tcp: Increase TCP_MAXSEG socket option minimum.

2010-11-11T05:35:37+00:00

As noted by Steve Chen, since commit
f5fff5dc8a7a3f395b0525c02ba92c95d42b7390 ("tcp: advertise MSS
requested by user") we can end up with a situation where
tcp_select_initial_window() does a divide by a zero (or
even negative) mss value.

The problem is that sometimes we effectively subtract
TCPOLEN_TSTAMP_ALIGNED and/or TCPOLEN_MD5SIG_ALIGNED from the mss.

Fix this by increasing the minimum from 8 to 64.

Reported-by: Steve Chen 
Signed-off-by: David S. Miller

net: avoid limits overflow

2010-11-10T20:12:00+00:00

Robin Holt tried to boot a 16TB machine and found some limits were
reached : sysctl_tcp_mem[2], sysctl_udp_mem[2]

We can switch infrastructure to use long "instead" of "int", now
atomic_long_t primitives are available for free.

Signed-off-by: Eric Dumazet 
Reported-by: Robin Holt 
Reviewed-by: Robin Holt 
Signed-off-by: Andrew Morton 
Signed-off-by: David S. Miller