1. 27 Apr, 2010 2 commits
  2. 20 Apr, 2010 1 commit
  3. 16 Apr, 2010 1 commit
    • Tom Herbert's avatar
      rfs: Receive Flow Steering · fec5e652
      Tom Herbert authored
      
      
      This patch implements receive flow steering (RFS).  RFS steers
      received packets for layer 3 and 4 processing to the CPU where
      the application for the corresponding flow is running.  RFS is an
      extension of Receive Packet Steering (RPS).
      
      The basic idea of RFS is that when an application calls recvmsg
      (or sendmsg) the application's running CPU is stored in a hash
      table that is indexed by the connection's rxhash which is stored in
      the socket structure.  The rxhash is passed in skb's received on
      the connection from netif_receive_skb.  For each received packet,
      the associated rxhash is used to look up the CPU in the hash table,
      if a valid CPU is set then the packet is steered to that CPU using
      the RPS mechanisms.
      
      The convolution of the simple approach is that it would potentially
      allow OOO packets.  If threads are thrashing around CPUs or multiple
      threads are trying to read from the same sockets, a quickly changing
      CPU value in the hash table could cause rampant OOO packets--
      we consider this a non-starter.
      
      To avoid OOO packets, this solution implements two types of hash
      tables: rps_sock_flow_table and rps_dev_flow_table.
      
      rps_sock_table is a global hash table.  Each entry is just a CPU
      number and it is populated in recvmsg and sendmsg as described above.
      This table contains the "desired" CPUs for flows.
      
      rps_dev_flow_table is specific to each device queue.  Each entry
      contains a CPU and a tail queue counter.  The CPU is the "current"
      CPU for a matching flow.  The tail queue counter holds the value
      of a tail queue counter for the associated CPU's backlog queue at
      the time of last enqueue for a flow matching the entry.
      
      Each backlog queue has a queue head counter which is incremented
      on dequeue, and so a queue tail counter is computed as queue head
      count + queue length.  When a packet is enqueued on a backlog queue,
      the current value of the queue tail counter is saved in the hash
      entry of the rps_dev_flow_table.
      
      And now the trick: when selecting the CPU for RPS (get_rps_cpu)
      the rps_sock_flow table and the rps_dev_flow table for the RX queue
      are consulted.  When the desired CPU for the flow (found in the
      rps_sock_flow table) does not match the current CPU (found in the
      rps_dev_flow table), the current CPU is changed to the desired CPU
      if one of the following is true:
      
      - The current CPU is unset (equal to RPS_NO_CPU)
      - Current CPU is offline
      - The current CPU's queue head counter >= queue tail counter in the
      rps_dev_flow table.  This checks if the queue tail has advanced
      beyond the last packet that was enqueued using this table entry.
      This guarantees that all packets queued using this entry have been
      dequeued, thus preserving in order delivery.
      
      Making each queue have its own rps_dev_flow table has two advantages:
      1) the tail queue counters will be written on each receive, so
      keeping the table local to interrupting CPU s good for locality.  2)
      this allows lockless access to the table-- the CPU number and queue
      tail counter need to be accessed together under mutual exclusion
      from netif_receive_skb, we assume that this is only called from
      device napi_poll which is non-reentrant.
      
      This patch implements RFS for TCP and connected UDP sockets.
      It should be usable for other flow oriented protocols.
      
      There are two configuration parameters for RFS.  The
      "rps_flow_entries" kernel init parameter sets the number of
      entries in the rps_sock_flow_table, the per rxqueue sysfs entry
      "rps_flow_cnt" contains the number of entries in the rps_dev_flow
      table for the rxqueue.  Both are rounded to power of two.
      
      The obvious benefit of RFS (over just RPS) is that it achieves
      CPU locality between the receive processing for a flow and the
      applications processing; this can result in increased performance
      (higher pps, lower latency).
      
      The benefits of RFS are dependent on cache hierarchy, application
      load, and other factors.  On simple benchmarks, we don't necessarily
      see improvement and sometimes see degradation.  However, for more
      complex benchmarks and for applications where cache pressure is
      much higher this technique seems to perform very well.
      
      Below are some benchmark results which show the potential benfit of
      this patch.  The netperf test has 500 instances of netperf TCP_RR
      test with 1 byte req. and resp.  The RPC test is an request/response
      test similar in structure to netperf RR test ith 100 threads on
      each host, but does more work in userspace that netperf.
      
      e1000e on 8 core Intel
         No RFS or RPS		104K tps at 30% CPU
         No RFS (best RPS config):    290K tps at 63% CPU
         RFS				303K tps at 61% CPU
      
      RPC test	tps	CPU%	50/90/99% usec latency	Latency StdDev
        No RFS/RPS	103K	48%	757/900/3185		4472.35
        RPS only:	174K	73%	415/993/2468		491.66
        RFS		223K	73%	379/651/1382		315.61
      Signed-off-by: default avatarTom Herbert <therbert@google.com>
      Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      fec5e652
  4. 08 Apr, 2010 1 commit
  5. 30 Mar, 2010 1 commit
    • Tejun Heo's avatar
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking... · 5a0e3ad6
      Tejun Heo authored
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
      
      percpu.h is included by sched.h and module.h and thus ends up being
      included when building most .c files.  percpu.h includes slab.h which
      in turn includes gfp.h making everything defined by the two files
      universally available and complicating inclusion dependencies.
      
      percpu.h -> slab.h dependency is about to be removed.  Prepare for
      this change by updating users of gfp and slab facilities include those
      headers directly instead of assuming availability.  As this conversion
      needs to touch large number of source files, the following script is
      used as the basis of conversion.
      
        http://userweb.kernel.org/~tj/misc/slabh-sweep.py
      
      
      
      The script does the followings.
      
      * Scan files for gfp and slab usages and update includes such that
        only the necessary includes are there.  ie. if only gfp is used,
        gfp.h, if slab is used, slab.h.
      
      * When the script inserts a new include, it looks at the include
        blocks and try to put the new include such that its order conforms
        to its surrounding.  It's put in the include block which contains
        core kernel includes, in the same order that the rest are ordered -
        alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
        doesn't seem to be any matching order.
      
      * If the script can't find a place to put a new include (mostly
        because the file doesn't have fitting include block), it prints out
        an error message indicating which .h file needs to be added to the
        file.
      
      The conversion was done in the following steps.
      
      1. The initial automatic conversion of all .c files updated slightly
         over 4000 files, deleting around 700 includes and adding ~480 gfp.h
         and ~3000 slab.h inclusions.  The script emitted errors for ~400
         files.
      
      2. Each error was manually checked.  Some didn't need the inclusion,
         some needed manual addition while adding it to implementation .h or
         embedding .c file was more appropriate for others.  This step added
         inclusions to around 150 files.
      
      3. The script was run again and the output was compared to the edits
         from #2 to make sure no file was left behind.
      
      4. Several build tests were done and a couple of problems were fixed.
         e.g. lib/decompress_*.c used malloc/free() wrappers around slab
         APIs requiring slab.h to be added manually.
      
      5. The script was run on all .h files but without automatically
         editing them as sprinkling gfp.h and slab.h inclusions around .h
         files could easily lead to inclusion dependency hell.  Most gfp.h
         inclusion directives were ignored as stuff from gfp.h was usually
         wildly available and often used in preprocessor macros.  Each
         slab.h inclusion directive was examined and added manually as
         necessary.
      
      6. percpu.h was updated not to include slab.h.
      
      7. Build test were done on the following configurations and failures
         were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
         distributed build env didn't work with gcov compiles) and a few
         more options had to be turned off depending on archs to make things
         build (like ipr on powerpc/64 which failed due to missing writeq).
      
         * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
         * powerpc and powerpc64 SMP allmodconfig
         * sparc and sparc64 SMP allmodconfig
         * ia64 SMP allmodconfig
         * s390 SMP allmodconfig
         * alpha SMP allmodconfig
         * um on x86_64 SMP allmodconfig
      
      8. percpu.h modifications were reverted so that it could be applied as
         a separate patch and serve as bisection point.
      
      Given the fact that I had only a couple of failures from tests on step
      6, I'm fairly confident about the coverage of this conversion patch.
      If there is a breakage, it's likely to be something in one of the arch
      headers which should be easily discoverable easily on most builds of
      the specific arch.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Guess-its-ok-by: default avatarChristoph Lameter <cl@linux-foundation.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      5a0e3ad6
  6. 05 Mar, 2010 2 commits
  7. 12 Feb, 2010 1 commit
  8. 17 Jan, 2010 1 commit
  9. 13 Dec, 2009 1 commit
  10. 23 Nov, 2009 1 commit
  11. 10 Nov, 2009 1 commit
  12. 08 Nov, 2009 6 commits
  13. 30 Oct, 2009 1 commit
  14. 18 Oct, 2009 2 commits
  15. 14 Oct, 2009 1 commit
  16. 13 Oct, 2009 1 commit
  17. 12 Oct, 2009 1 commit
    • Neil Horman's avatar
      net: Generalize socket rx gap / receive queue overflow cmsg · 3b885787
      Neil Horman authored
      Create a new socket level option to report number of queue overflows
      
      Recently I augmented the AF_PACKET protocol to report the number of frames lost
      on the socket receive queue between any two enqueued frames.  This value was
      exported via a SOL_PACKET level cmsg.  AFter I completed that work it was
      requested that this feature be generalized so that any datagram oriented socket
      could make use of this option.  As such I've created this patch, It creates a
      new SOL_SOCKET level option called SO_RXQ_OVFL, which when enabled exports a
      SOL_SOCKET level cmsg that reports the nubmer of times the sk_receive_queue
      overflowed between any two given frames.  It also augments the AF_PACKET
      protocol to take advantage of this new feature (as it previously did not touch
      sk->sk_drops, which this patch uses to record the overflow count).  Tested
      successfully by me.
      
      Notes:
      
      1) Unlike my previous patch, this patch simply records the sk_drops value, which
      is not a number of drops between packets, but rather a total number of drops.
      Deltas must be computed in user space.
      
      2) While this patch currently works with datagram oriented protocols, it will
      also be accepted by non-datagram oriented protocols. I'm not sure if thats
      agreeable to everyone, but my argument in favor of doing so is that, for those
      protocols which aren't applicable to this option, sk_drops will always be zero,
      and reporting no drops on a receive queue that isn't used for those
      non-participating protocols seems reasonable to me.  This also saves us having
      to code in a per-protocol opt in mechanism.
      
      3) This applies cleanly to net-next assuming that commit
      97775007
      
       (my af packet cmsg patch) is reverted
      Signed-off-by: default avatarNeil Horman <nhorman@tuxdriver.com>
      Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      3b885787
  18. 07 Oct, 2009 1 commit
    • Eric Dumazet's avatar
      udp: dynamically size hash tables at boot time · f86dcc5a
      Eric Dumazet authored
      
      
      UDP_HTABLE_SIZE was initialy defined to 128, which is a bit small for
      several setups.
      
      4000 active UDP sockets -> 32 sockets per chain in average. An
      incoming frame has to lookup all sockets to find best match, so long
      chains hurt latency.
      
      Instead of a fixed size hash table that cant be perfect for every
      needs, let UDP stack choose its table size at boot time like tcp/ip
      route, using alloc_large_system_hash() helper
      
      Add an optional boot parameter, uhash_entries=x so that an admin can
      force a size between 256 and 65536 if needed, like thash_entries and
      rhash_entries.
      
      dmesg logs two new lines :
      [    0.647039] UDP hash table entries: 512 (order: 0, 4096 bytes)
      [    0.647099] UDP Lite hash table entries: 512 (order: 0, 4096 bytes)
      
      Maximal size on 64bit arches would be 65536 slots, ie 1 MBytes for non
      debugging spinlocks.
      Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      f86dcc5a
  19. 01 Oct, 2009 1 commit
  20. 30 Sep, 2009 1 commit
  21. 02 Sep, 2009 1 commit
    • Eric Dumazet's avatar
      ip: Report qdisc packet drops · 6ce9e7b5
      Eric Dumazet authored
      
      
      Christoph Lameter pointed out that packet drops at qdisc level where not
      accounted in SNMP counters. Only if application sets IP_RECVERR, drops
      are reported to user (-ENOBUFS errors) and SNMP counters updated.
      
      IP_RECVERR is used to enable extended reliable error message passing,
      but these are not needed to update system wide SNMP stats.
      
      This patch changes things a bit to allow SNMP counters to be updated,
      regardless of IP_RECVERR being set or not on the socket.
      
      Example after an UDP tx flood
      # netstat -s 
      ...
      IP:
          1487048 outgoing packets dropped
      ...
      Udp:
      ...
          SndbufErrors: 1487048
      
      
      send() syscalls, do however still return an OK status, to not
      break applications.
      
      Note : send() manual page explicitly says for -ENOBUFS error :
      
       "The output queue for a network interface was full.
        This generally indicates that the interface has stopped sending,
        but may be caused by transient congestion.
        (Normally, this does not occur in Linux. Packets are just silently
        dropped when a device queue overflows.) "
      
      This is not true for IP_RECVERR enabled sockets : a send() syscall
      that hit a qdisc drop returns an ENOBUFS error.
      
      Many thanks to Christoph, David, and last but not least, Alexey !
      Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      6ce9e7b5
  22. 17 Jul, 2009 1 commit
  23. 12 Jul, 2009 1 commit
  24. 18 Jun, 2009 1 commit
  25. 03 Jun, 2009 1 commit
  26. 11 Apr, 2009 1 commit
    • Vlad Yasevich's avatar
      ipv6: Fix NULL pointer dereference with time-wait sockets · 499923c7
      Vlad Yasevich authored
      Commit b2f5e7cd
      
      
      (ipv6: Fix conflict resolutions during ipv6 binding)
      introduced a regression where time-wait sockets were
      not treated correctly.  This resulted in the following:
      
      BUG: unable to handle kernel NULL pointer dereference at 0000000000000062
      IP: [<ffffffff805d7d61>] ipv4_rcv_saddr_equal+0x61/0x70
      ...
      Call Trace:
      [<ffffffffa033847b>] ipv6_rcv_saddr_equal+0x1bb/0x250 [ipv6]
      [<ffffffffa03505a8>] inet6_csk_bind_conflict+0x88/0xd0 [ipv6]
      [<ffffffff805bb18e>] inet_csk_get_port+0x1ee/0x400
      [<ffffffffa0319b7f>] inet6_bind+0x1cf/0x3a0 [ipv6]
      [<ffffffff8056d17c>] ? sockfd_lookup_light+0x3c/0xd0
      [<ffffffff8056ed49>] sys_bind+0x89/0x100
      [<ffffffff80613ea2>] ? trace_hardirqs_on_thunk+0x3a/0x3c
      [<ffffffff8020bf9b>] system_call_fastpath+0x16/0x1b
      Tested-by: default avatarBrian Haley <brian.haley@hp.com>
      Tested-by: default avatarEd Tomlinson <edt@aei.ca>
      Signed-off-by: default avatarVlad Yasevich <vladislav.yasevich@hp.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      499923c7
  27. 24 Mar, 2009 1 commit
  28. 23 Mar, 2009 1 commit
    • Vitaly Mayatskikh's avatar
      udp: Wrong locking code in udp seq_file infrastructure · 30842f29
      Vitaly Mayatskikh authored
      
      
      Reading zero bytes from /proc/net/udp or other similar files which use
      the same seq_file udp infrastructure panics kernel in that way:
      
      =====================================
      [ BUG: bad unlock balance detected! ]
      -------------------------------------
      read/1985 is trying to release lock (&table->hash[i].lock) at:
      [<ffffffff81321d83>] udp_seq_stop+0x27/0x29
      but there are no more locks to release!
      
      other info that might help us debug this:
      1 lock held by read/1985:
       #0:  (&p->lock){--..}, at: [<ffffffff810eefb6>] seq_read+0x38/0x348
      
      stack backtrace:
      Pid: 1985, comm: read Not tainted 2.6.29-rc8 #9
      Call Trace:
       [<ffffffff81321d83>] ? udp_seq_stop+0x27/0x29
       [<ffffffff8106dab9>] print_unlock_inbalance_bug+0xd6/0xe1
       [<ffffffff8106db62>] lock_release_non_nested+0x9e/0x1c6
       [<ffffffff810ef030>] ? seq_read+0xb2/0x348
       [<ffffffff8106bdba>] ? mark_held_locks+0x68/0x86
       [<ffffffff81321d83>] ? udp_seq_stop+0x27/0x29
       [<ffffffff8106dde7>] lock_release+0x15d/0x189
       [<ffffffff8137163c>] _spin_unlock_bh+0x1e/0x34
       [<ffffffff81321d83>] udp_seq_stop+0x27/0x29
       [<ffffffff810ef239>] seq_read+0x2bb/0x348
       [<ffffffff810eef7e>] ? seq_read+0x0/0x348
       [<ffffffff8111aedd>] proc_reg_read+0x90/0xaf
       [<ffffffff810d878f>] vfs_read+0xa6/0x103
       [<ffffffff8106bfac>] ? trace_hardirqs_on_caller+0x12f/0x153
       [<ffffffff810d88a2>] sys_read+0x45/0x69
       [<ffffffff8101123a>] system_call_fastpath+0x16/0x1b
      BUG: scheduling while atomic: read/1985/0xffffff00
      INFO: lockdep is turned off.
      Modules linked in: cpufreq_ondemand acpi_cpufreq freq_table dm_multipath kvm ppdev snd_hda_codec_analog snd_hda_intel snd_hda_codec snd_hwdep snd_seq_dummy snd_seq_oss snd_seq_midi_event arc4 snd_s
      eq ecb thinkpad_acpi snd_seq_device iwl3945 hwmon sdhci_pci snd_pcm_oss sdhci rfkill mmc_core snd_mixer_oss i2c_i801 mac80211 yenta_socket ricoh_mmc i2c_core iTCO_wdt snd_pcm iTCO_vendor_support rs
      rc_nonstatic snd_timer snd lib80211 cfg80211 soundcore snd_page_alloc video parport_pc output parport e1000e [last unloaded: scsi_wait_scan]
      Pid: 1985, comm: read Not tainted 2.6.29-rc8 #9
      Call Trace:
       [<ffffffff8106b456>] ? __debug_show_held_locks+0x1b/0x24
       [<ffffffff81043660>] __schedule_bug+0x7e/0x83
       [<ffffffff8136ede9>] schedule+0xce/0x838
       [<ffffffff810d7972>] ? fsnotify_access+0x5f/0x67
       [<ffffffff810112d0>] ? sysret_careful+0xb/0x37
       [<ffffffff8106be9c>] ? trace_hardirqs_on_caller+0x1f/0x153
       [<ffffffff8137127b>] ? trace_hardirqs_on_thunk+0x3a/0x3f
       [<ffffffff810112f6>] sysret_careful+0x31/0x37
      read[1985]: segfault at 7fffc479bfe8 ip 0000003e7420a180 sp 00007fffc479bfa0 error 6
      Kernel panic - not syncing: Aiee, killing interrupt handler!
      
      udp_seq_stop() tries to unlock not yet locked spinlock. The lock was lost
      during splitting global udp_hash_lock to subsequent spinlocks.
      
      Signed-off by: Vitaly Mayatskikh <v.mayatskih@gmail.com>
      Acked-by: default avatarEric Dumazet <dada1@cosmosbay.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      30842f29
  29. 13 Mar, 2009 1 commit
  30. 15 Feb, 2009 1 commit
  31. 06 Feb, 2009 1 commit
  32. 05 Feb, 2009 1 commit