linux-stable.git/net/core/sock.c, branch linux-3.11.y

tcp: TSO packets automatic sizing

2013-11-04T12:35:11+00:00

[ Upstream commits 6d36824e730f247b602c90e8715a792003e3c5a7,
  02cf4ebd82ff0ac7254b88e466820a290ed8289a, and parts of
  7eec4174ff29cd42f2acfae8112f51c228545d40 ]

After hearing many people over past years complaining against TSO being
bursty or even buggy, we are proud to present automatic sizing of TSO
packets.

One part of the problem is that tcp_tso_should_defer() uses an heuristic
relying on upcoming ACKS instead of a timer, but more generally, having
big TSO packets makes little sense for low rates, as it tends to create
micro bursts on the network, and general consensus is to reduce the
buffering amount.

This patch introduces a per socket sk_pacing_rate, that approximates
the current sending rate, and allows us to size the TSO packets so
that we try to send one packet every ms.

This field could be set by other transports.

Patch has no impact for high speed flows, where having large TSO packets
makes sense to reach line rate.

For other flows, this helps better packet scheduling and ACK clocking.

This patch increases performance of TCP flows in lossy environments.

A new sysctl (tcp_min_tso_segs) is added, to specify the
minimal size of a TSO packet (default being 2).

A follow-up patch will provide a new packet scheduler (FQ), using
sk_pacing_rate as an input to perform optional per flow pacing.

This explains why we chose to set sk_pacing_rate to twice the current
rate, allowing 'slow start' ramp up.

sk_pacing_rate = 2 * cwnd * mss / srtt

v2: Neal Cardwell reported a suspect deferring of last two segments on
initial write of 10 MSS, I had to change tcp_tso_should_defer() to take
into account tp->xmit_size_goal_segs

Signed-off-by: Eric Dumazet 
Cc: Neal Cardwell 
Cc: Yuchung Cheng 
Cc: Van Jacobson 
Cc: Tom Herbert 
Acked-by: Yuchung Cheng 
Acked-by: Neal Cardwell 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: rename CONFIG_NET_LL_RX_POLL to CONFIG_NET_RX_BUSY_POLL

2013-08-01T22:11:17+00:00

Eliezer renames several *ll_poll to *busy_poll, but forgets
CONFIG_NET_LL_RX_POLL, so in case of confusion, rename it too.

Cc: Eliezer Tamir 
Cc: David S. Miller 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller

net: rename busy poll socket op and globals

2013-07-11T00:08:27+00:00

Rename LL_SO to BUSY_POLL_SO
Rename sysctl_net_ll_{read,poll} to sysctl_busy_{read,poll}
Fix up users of these variables.
Fix documentation for sysctl.

a patch for the socket.7  man page will follow separately,
because of limitations of my mail setup.

Signed-off-by: Eliezer Tamir 
Signed-off-by: David S. Miller

net: rename include/net/ll_poll.h to include/net/busy_poll.h

2013-07-11T00:08:27+00:00

Rename the file and correct all the places where it is included.

Signed-off-by: Eliezer Tamir 
Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2013-07-03T21:55:13+00:00

Conflicts:
	drivers/net/ethernet/freescale/fec_main.c
	drivers/net/ethernet/renesas/sh_eth.c
	net/ipv4/gre.c

The GRE conflict is between a bug fix (kfree_skb --> kfree_skb_list)
and the splitting of the gre.c code into seperate files.

The FEC conflict was two sets of changes adding ethtool support code
in an "!CONFIG_M5272" CPP protected block.

Finally the sh_eth.c conflict was between one commit add bits set
in the .eesr_err_check mask whilst another commit removed the
.tx_error_check member and assignments.

Signed-off-by: David S. Miller

net: fix kernel deadlock with interface rename and netdev name retrieval.

2013-06-26T20:42:54+00:00

When the kernel (compiled with CONFIG_PREEMPT=n) is performing the
rename of a network interface, it can end up waiting for a workqueue
to complete. If userland is able to invoke a SIOCGIFNAME ioctl or a
SO_BINDTODEVICE getsockopt in between, the kernel will deadlock due to
the fact that read_secklock_begin() will spin forever waiting for the
writer process (the one doing the interface rename) to update the
devnet_rename_seq sequence.

This patch fixes the problem by adding a helper (netdev_get_name())
and using it in the code handling the SIOCGIFNAME ioctl and
SO_BINDTODEVICE setsockopt.

The netdev_get_name() helper uses raw_seqcount_begin() to avoid
spinning forever, waiting for devnet_rename_seq->sequence to become
even. cond_resched() is used in the contended case, before retrying
the access to give the writer process a chance to finish.

The use of raw_seqcount_begin() will incur some unneeded work in the
reader process in the contended case, but this is better than
deadlocking the system.

Signed-off-by: Nicolas Schichan 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: poll/select low latency socket support

2013-06-25T23:35:52+00:00

select/poll busy-poll support.

Split sysctl value into two separate ones, one for read and one for poll.
updated Documentation/sysctl/net.txt

Add a new poll flag POLL_LL. When this flag is set, sock_poll will call
sk_poll_ll if possible. sock_poll sets this flag in its return value
to indicate to select/poll when a socket that can busy poll is found.

When poll/select have nothing to report, call the low-level
sock_poll again until we are out of time or we find something.

Once the system call finds something, it stops setting POLL_LL, so it can
return the result to the user ASAP.

Signed-off-by: Eliezer Tamir 
Signed-off-by: David S. Miller

net: add socket option for low latency polling

2013-06-17T22:48:14+00:00

adds a socket option for low latency polling.
This allows overriding the global sysctl value with a per-socket one.
Unexport sysctl_net_ll_poll since for now it's not needed in modules.

Signed-off-by: Eliezer Tamir 
Signed-off-by: David S. Miller

net: add low latency socket poll

2013-06-11T04:22:35+00:00

Adds an ndo_ll_poll method and the code that supports it.
This method can be used by low latency applications to busy-poll
Ethernet device queues directly from the socket code.
sysctl_net_ll_poll controls how many microseconds to poll.
Default is zero (disabled).
Individual protocol support will be added by subsequent patches.

Signed-off-by: Alexander Duyck 
Signed-off-by: Jesse Brandeburg 
Signed-off-by: Eliezer Tamir 
Acked-by: Eric Dumazet 
Tested-by: Willem de Bruijn 
Signed-off-by: David S. Miller

net/core/sock.c: add missing VSOCK string in af_family_*_key_strings

2013-05-29T06:58:49+00:00

The three arrays of strings: af_family_key_strings,
af_family_slock_key_strings and af_family_clock_key_strings have not
VSOCK's string

Signed-off-by: Federico Vaga 
Signed-off-by: David S. Miller