linux/net/ipv4/proc.c, branch v3.5

tcp: reduce out_of_order memory use

2012-03-19T20:53:08Z

With increasing receive window sizes, but speed of light not improved that much, out of order queue can contain a huge number of skbs, waiting to be moved to receive_queue when missing packets can fill the holes. Some devices happen to use fat skbs (truesize of 4096 + sizeof(struct sk_buff)) to store regular (MTU <= 1500) frames. This makes highly probable sk_rmem_alloc hits sk_rcvbuf limit, which can be 4Mbytes in many cases. When limit is hit, tcp stack calls tcp_collapse_ofo_queue(), a true latency killer and cpu cache blower. Doing the coalescing attempt each time we add a frame in ofo queue permits to keep memory use tight and in many cases avoid the tcp_collapse() thing later. Tested on various wireless setups (b43, ath9k, ...) known to use big skb truesize, this patch removed the "packets collapsed in receive queue due to low socket buffer" I had before. This also reduced average memory used by tcp sockets. With help from Neal Cardwell. Signed-off-by: Eric Dumazet Cc: Neal Cardwell Cc: Yuchung Cheng Cc: H.K. Jerry Chu Cc: Tom Herbert Cc: Ilpo Järvinen Acked-by: Neal Cardwell Signed-off-by: David S. Miller

tcp: add LINUX_MIB_TCPRETRANSFAIL counter

2012-01-26T18:51:00Z

It might be useful to get a counter of failed tcp_retransmit_skb() calls. Reported-by: Satoru Moriya Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

tcp: detect loss above high_seq in recovery

2012-01-22T20:08:44Z

Correctly implement a loss detection heuristic: New sequences (above high_seq) sent during the fast recovery are deemed lost when higher sequences are SACKed. Current code does not catch these losses, because tcp_mark_head_lost() does not check packets beyond high_seq. The fix is straight-forward by checking packets until the highest sacked packet. In addition, all the FLAG_DATA_LOST logic are in-effective and redundant and can be removed. Update the loss heuristic comments. The algorithm above is documented as heuristic B, but it is redundant too because heuristic A already covers B. Note that this change only marks some forward-retransmitted packets LOST. It does NOT forbid TCP performing further CWR on new losses. A potential follow-up patch under preparation is to perform another CWR on "new" losses such as 1) sequence above high_seq is lost (by resetting high_seq to snd_nxt) 2) retransmission is lost. Signed-off-by: Yuchung Cheng Signed-off-by: David S. Miller

foundations of per-cgroup memory pressure controlling.

2011-12-13T00:04:10Z

This patch replaces all uses of struct sock fields' memory_pressure, memory_allocated, sockets_allocated, and sysctl_mem to acessor macros. Those macros can either receive a socket argument, or a mem_cgroup argument, depending on the context they live in. Since we're only doing a macro wrapping here, no performance impact at all is expected in the case where we don't have cgroups disabled. Signed-off-by: Glauber Costa Reviewed-by: Hiroyouki Kamezawa CC: David S. Miller CC: Eric W. Biederman CC: Eric Dumazet Signed-off-by: David S. Miller

ipv4: reduce percpu needs for icmpmsg mibs

2011-11-09T21:04:20Z

Reading /proc/net/snmp on a machine with a lot of cpus is very expensive (can be ~88000 us). This is because ICMPMSG MIB uses 4096 bytes per cpu, and folding values for all possible cpus can read 16 Mbytes of memory. ICMP messages are not considered as fast path on a typical server, and eventually few cpus handle them anyway. We can afford an atomic operation instead of using percpu data. This saves 4096 bytes per cpu and per network namespace. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

net: Add export.h for EXPORT_SYMBOL/THIS_MODULE to non-modules

2011-10-31T23:30:30Z

These files are non modular, but need to export symbols using the macros now living in export.h -- call out the include so that things won't break when we remove the implicit presence of module.h from everywhere. Signed-off-by: Paul Gortmaker

tcp: Change possible SYN flooding messages

2011-09-15T18:49:43Z

"Possible SYN flooding on port xxxx " messages can fill logs on servers. Change logic to log the message only once per listener, and add two new SNMP counters to track : TCPReqQFullDoCookies : number of times a SYNCOOKIE was replied to client TCPReqQFullDrop : number of times a SYN request was dropped because syncookies were not enabled. Based on a prior patch from Tom Herbert, and suggestions from David. Signed-off-by: Eric Dumazet CC: Tom Herbert Signed-off-by: David S. Miller

tcp: Replace time wait bucket msg by counter

2010-12-08T20:16:33Z

Rather than printing the message to the log, use a mib counter to keep track of the count of occurences of time wait bucket overflow. Reduces spam in logs. Signed-off-by: Tom Herbert Signed-off-by: David S. Miller

net: avoid limits overflow

2010-11-10T20:12:00Z

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

snmp: 64bit ipstats_mib for all arches

2010-06-30T20:31:19Z

/proc/net/snmp and /proc/net/netstat expose SNMP counters. Width of these counters is either 32 or 64 bits, depending on the size of "unsigned long" in kernel. This means user program parsing these files must already be prepared to deal with 64bit values, regardless of user program being 32 or 64 bit. This patch introduces 64bit snmp values for IPSTAT mib, where some counters can wrap pretty fast if they are 32bit wide. # netstat -s|egrep "InOctets|OutOctets" InOctets: 244068329096 OutOctets: 244069348848 Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller