1. 01 Mar, 2011 3 commits
  2. 24 Jan, 2011 1 commit
  3. 16 Dec, 2010 2 commits
  4. 17 Nov, 2010 1 commit
  5. 16 Nov, 2010 1 commit
  6. 10 Nov, 2010 1 commit
  7. 25 Oct, 2010 1 commit
  8. 09 Sep, 2010 1 commit
    • Eric Dumazet's avatar
      udp: add rehash on connect() · 719f8358
      Eric Dumazet authored
      commit 30fff923
      
       introduced in linux-2.6.33 (udp: bind() optimisation)
      added a secondary hash on UDP, hashed on (local addr, local port).
      
      Problem is that following sequence :
      
      fd = socket(...)
      connect(fd, &remote, ...)
      
      not only selects remote end point (address and port), but also sets
      local address, while UDP stack stored in secondary hash table the socket
      while its local address was INADDR_ANY (or ipv6 equivalent)
      
      Sequence is :
       - autobind() : choose a random local port, insert socket in hash tables
                    [while local address is INADDR_ANY]
       - connect() : set remote address and port, change local address to IP
                    given by a route lookup.
      
      When an incoming UDP frame comes, if more than 10 sockets are found in
      primary hash table, we switch to secondary table, and fail to find
      socket because its local address changed.
      
      One solution to this problem is to rehash datagram socket if needed.
      
      We add a new rehash(struct socket *) method in "struct proto", and
      implement this method for UDP v4 & v6, using a common helper.
      
      This rehashing only takes care of secondary hash table, since primary
      hash (based on local port only) is not changed.
      Reported-by: default avatarKrzysztof Piotr Oledzki <ole@ans.pl>
      Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
      Tested-by: default avatarKrzysztof Piotr Oledzki <ole@ans.pl>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      719f8358
  9. 19 Aug, 2010 1 commit
  10. 11 Jun, 2010 1 commit
  11. 01 Jun, 2010 1 commit
  12. 29 May, 2010 1 commit
  13. 27 May, 2010 1 commit
    • Eric Dumazet's avatar
      net: fix lock_sock_bh/unlock_sock_bh · 8a74ad60
      Eric Dumazet authored
      
      
      This new sock lock primitive was introduced to speedup some user context
      socket manipulation. But it is unsafe to protect two threads, one using
      regular lock_sock/release_sock, one using lock_sock_bh/unlock_sock_bh
      
      This patch changes lock_sock_bh to be careful against 'owned' state.
      If owned is found to be set, we must take the slow path.
      lock_sock_bh() now returns a boolean to say if the slow path was taken,
      and this boolean is used at unlock_sock_bh time to call the appropriate
      unlock function.
      
      After this change, BH are either disabled or enabled during the
      lock_sock_bh/unlock_sock_bh protected section. This might be misleading,
      so we rename these functions to lock_sock_fast()/unlock_sock_fast().
      Reported-by: default avatarAnton Blanchard <anton@samba.org>
      Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
      Tested-by: default avatarAnton Blanchard <anton@samba.org>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      8a74ad60
  14. 25 May, 2010 1 commit
  15. 16 May, 2010 1 commit
  16. 07 May, 2010 1 commit
  17. 28 Apr, 2010 2 commits
    • Eric Dumazet's avatar
      net: ip_queue_rcv_skb() helper · f84af32c
      Eric Dumazet authored
      
      
      When queueing a skb to socket, we can immediately release its dst if
      target socket do not use IP_CMSG_PKTINFO.
      
      tcp_data_queue() can drop dst too.
      
      This to benefit from a hot cache line and avoid the receiver, possibly
      on another cpu, to dirty this cache line himself.
      Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      f84af32c
    • Eric Dumazet's avatar
      net: speedup udp receive path · 4b0b72f7
      Eric Dumazet authored
      Since commit 95766fff
      
       ([UDP]: Add memory accounting.), 
      each received packet needs one extra sock_lock()/sock_release() pair.
      
      This added latency because of possible backlog handling. Then later,
      ticket spinlocks added yet another latency source in case of DDOS.
      
      This patch introduces lock_sock_bh() and unlock_sock_bh()
      synchronization primitives, avoiding one atomic operation and backlog
      processing.
      
      skb_free_datagram_locked() uses them instead of full blown
      lock_sock()/release_sock(). skb is orphaned inside locked section for
      proper socket memory reclaim, and finally freed outside of it.
      
      UDP receive path now take the socket spinlock only once.
      Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      4b0b72f7
  18. 27 Apr, 2010 2 commits
  19. 21 Apr, 2010 1 commit
  20. 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
  21. 08 Apr, 2010 1 commit
  22. 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
  23. 05 Mar, 2010 2 commits
  24. 13 Feb, 2010 1 commit
  25. 18 Jan, 2010 1 commit
  26. 14 Dec, 2009 1 commit
  27. 23 Nov, 2009 1 commit
  28. 11 Nov, 2009 1 commit
  29. 09 Nov, 2009 6 commits