1. 16 5月, 2010 1 次提交
  2. 28 4月, 2010 1 次提交
  3. 21 4月, 2010 2 次提交
  4. 17 4月, 2010 1 次提交
    • T
      rfs: Receive Flow Steering · fec5e652
      Tom Herbert 提交于
      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: NTom Herbert <therbert@google.com>
      Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      fec5e652
  5. 13 4月, 2010 1 次提交
    • E
      net: sk_dst_cache RCUification · b6c6712a
      Eric Dumazet 提交于
      With latest CONFIG_PROVE_RCU stuff, I felt more comfortable to make this
      work.
      
      sk->sk_dst_cache is currently protected by a rwlock (sk_dst_lock)
      
      This rwlock is readlocked for a very small amount of time, and dst
      entries are already freed after RCU grace period. This calls for RCU
      again :)
      
      This patch converts sk_dst_lock to a spinlock, and use RCU for readers.
      
      __sk_dst_get() is supposed to be called with rcu_read_lock() or if
      socket locked by user, so use appropriate rcu_dereference_check()
      condition (rcu_read_lock_held() || sock_owned_by_user(sk))
      
      This patch avoids two atomic ops per tx packet on UDP connected sockets,
      for example, and permits sk_dst_lock to be much less dirtied.
      Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      b6c6712a
  6. 02 4月, 2010 1 次提交
  7. 30 3月, 2010 1 次提交
    • T
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking... · 5a0e3ad6
      Tejun Heo 提交于
      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: NTejun Heo <tj@kernel.org>
      Guess-its-ok-by: NChristoph Lameter <cl@linux-foundation.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      5a0e3ad6
  8. 22 3月, 2010 1 次提交
  9. 17 2月, 2010 1 次提交
    • T
      percpu: add __percpu sparse annotations to net · 7d720c3e
      Tejun Heo 提交于
      Add __percpu sparse annotations to net.
      
      These annotations are to make sparse consider percpu variables to be
      in a different address space and warn if accessed without going
      through percpu accessors.  This patch doesn't affect normal builds.
      
      The macro and type tricks around snmp stats make things a bit
      interesting.  DEFINE/DECLARE_SNMP_STAT() macros mark the target field
      as __percpu and SNMP_UPD_PO_STATS() macro is updated accordingly.  All
      snmp_mib_*() users which used to cast the argument to (void **) are
      updated to cast it to (void __percpu **).
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Acked-by: NDavid S. Miller <davem@davemloft.net>
      Cc: Patrick McHardy <kaber@trash.net>
      Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
      Cc: Vlad Yasevich <vladislav.yasevich@hp.com>
      Cc: netdev@vger.kernel.org
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      7d720c3e
  10. 06 11月, 2009 3 次提交
  11. 29 10月, 2009 1 次提交
  12. 19 10月, 2009 1 次提交
    • E
      inet: rename some inet_sock fields · c720c7e8
      Eric Dumazet 提交于
      In order to have better cache layouts of struct sock (separate zones
      for rx/tx paths), we need this preliminary patch.
      
      Goal is to transfert fields used at lookup time in the first
      read-mostly cache line (inside struct sock_common) and move sk_refcnt
      to a separate cache line (only written by rx path)
      
      This patch adds inet_ prefix to daddr, rcv_saddr, dport, num, saddr,
      sport and id fields. This allows a future patch to define these
      fields as macros, like sk_refcnt, without name clashes.
      Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c720c7e8
  13. 07 10月, 2009 1 次提交
  14. 02 10月, 2009 1 次提交
  15. 15 9月, 2009 1 次提交
  16. 29 8月, 2009 1 次提交
  17. 13 7月, 2009 1 次提交
  18. 04 6月, 2009 1 次提交
  19. 02 6月, 2009 1 次提交
    • N
      ipv4: New multicast-all socket option · f771bef9
      Nivedita Singhvi 提交于
      After some discussion offline with Christoph Lameter and David Stevens
      regarding multicast behaviour in Linux, I'm submitting a slightly
      modified patch from the one Christoph submitted earlier.
      
      This patch provides a new socket option IP_MULTICAST_ALL.
      
      In this case, default behaviour is _unchanged_ from the current
      Linux standard. The socket option is set by default to provide
      original behaviour. Sockets wishing to receive data only from
      multicast groups they join explicitly will need to clear this
      socket option.
      Signed-off-by: NNivedita Singhvi <niv@us.ibm.com>
      Signed-off-by: Christoph Lameter<cl@linux.com>
      Acked-by: NDavid Stevens <dlstevens@us.ibm.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      f771bef9
  20. 27 5月, 2009 2 次提交
  21. 17 4月, 2009 1 次提交
    • E
      [PATCH] net: remove superfluous call to synchronize_net() · 573636cb
      Eric Dumazet 提交于
      inet_register_protosw() function is responsible for adding a new
      inet protocol into a global table (inetsw[]) that is used with RCU rules.
      
      As soon as the store of the pointer is done, other cpus might see
      this new protocol in inetsw[], so we have to make sure new protocol
      is ready for use. All pending memory updates should thus be committed
      to memory before setting the pointer.
      This is correctly done using rcu_assign_pointer()
      
      synchronize_net() is typically used at unregister time, after
      unsetting the pointer, to make sure no other cpu is still using
      the object we want to dismantle. Using it at register time
      is only adding an artificial delay that could hide a real bug,
      and this bug could popup if/when synchronize_rcu() can proceed
      faster than now.
      
      This saves about 13 ms on boot time on a HZ=1000 8 cpus machine  ;) 
      (4 calls to inet_register_protosw(), and about 3200 us per call)
      Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      573636cb
  22. 10 3月, 2009 1 次提交
  23. 20 2月, 2009 1 次提交
  24. 09 2月, 2009 1 次提交
  25. 02 2月, 2009 1 次提交
  26. 01 2月, 2009 1 次提交
  27. 30 1月, 2009 1 次提交
    • H
      gro: Avoid copying headers of unmerged packets · 86911732
      Herbert Xu 提交于
      Unfortunately simplicity isn't always the best.  The fraginfo
      interface turned out to be suboptimal.  The problem was quite
      obvious.  For every packet, we have to copy the headers from
      the frags structure into skb->head, even though for 99% of the
      packets this part is immediately thrown away after the merge.
      
      LRO didn't have this problem because it directly read the headers
      from the frags structure.
      
      This patch attempts to address this by creating an interface
      that allows GRO to access the headers in the first frag without
      having to copy it.  Because all drivers that use frags place the
      headers in the first frag this optimisation should be enough.
      Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      86911732
  28. 26 12月, 2008 1 次提交
  29. 16 12月, 2008 2 次提交
    • H
      tcp: Add GRO support · bf296b12
      Herbert Xu 提交于
      This patch adds the TCP-specific portion of GRO.  The criterion for
      merging is extremely strict (the TCP header must match exactly apart
      from the checksum) so as to allow refragmentation.  Otherwise this
      is pretty much identical to LRO, except that we support the merging
      of ECN packets.
      Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      bf296b12
    • H
      ipv4: Add GRO infrastructure · 73cc19f1
      Herbert Xu 提交于
      This patch adds GRO support for IPv4.
      
      The criteria for merging is more stringent than LRO, in particular,
      we require all fields in the IP header to be identical except for
      the length, ID and checksum.  In addition, the ID must form an
      arithmetic sequence with a difference of one.
      
      The ID requirement might seem overly strict, however, most hardware
      TSO solutions already obey this rule.  Linux itself also obeys this
      whether GSO is in use or not.
      
      In future we could relax this rule by storing the IDs (or rather
      making sure that we don't drop them when pulling the aggregate
      skb's tail).
      Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      73cc19f1
  30. 24 11月, 2008 1 次提交
  31. 20 11月, 2008 1 次提交
  32. 31 10月, 2008 1 次提交
  33. 01 10月, 2008 1 次提交
  34. 27 7月, 2008 1 次提交
  35. 26 7月, 2008 1 次提交