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  1. 28 10月, 2008 1 次提交
    • N
      net: implement emergency route cache rebulds when gc_elasticity is exceeded · 1080d709
      由 Neil Horman 提交于 
      This is a patch to provide on demand route cache rebuilding.  Currently, our
route cache is rebulid periodically regardless of need.  This introduced
unneeded periodic latency.  This patch offers a better approach.  Using code
provided by Eric Dumazet, we compute the standard deviation of the average hash
bucket chain length while running rt_check_expire.  Should any given chain
length grow to larger that average plus 4 standard deviations, we trigger an
emergency hash table rebuild for that net namespace.  This allows for the common
case in which chains are well behaved and do not grow unevenly to not incur any
latency at all, while those systems (which may be being maliciously attacked),
only rebuild when the attack is detected.  This patch take 2 other factors into
account:
1) chains with multiple entries that differ by attributes that do not affect the
hash value are only counted once, so as not to unduly bias system to rebuilding
if features like QOS are heavily used
2) if rebuilding crosses a certain threshold (which is adjustable via the added
sysctl in this patch), route caching is disabled entirely for that net
namespace, since constant rebuilding is less efficient that no caching at all

Tested successfully by me.
Signed-off-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1080d709
  3. 20 10月, 2008 1 次提交
  5. 09 10月, 2008 1 次提交
  7. 08 10月, 2008 16 次提交
  9. 23 7月, 2008 1 次提交
  11. 18 7月, 2008 8 次提交
  13. 06 7月, 2008 3 次提交
  15. 17 6月, 2008 1 次提交
    • P
      netns: introduce the net_hash_mix "salt" for hashes · 0b441916
      由 Pavel Emelyanov 提交于 
      There are many possible ways to add this "salt", thus I made this
patch to be the last in the series to change it if required.

Currently I propose to use the struct net pointer itself as this 
salt, but since this pointer is most often cache-line aligned, shift 
this right to eliminate the bits, that are most often zeroed.

After this, simply add this mix to prepared hashfn-s.

For CONFIG_NET_NS=n case this salt is 0 and no changes in hashfn
appear.
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      0b441916
  17. 10 6月, 2008 2 次提交
  19. 15 4月, 2008 1 次提交
    • P
      [NETNS]: The generic per-net pointers. · dec827d1
      由 Pavel Emelyanov 提交于 
      Add the elastic array of void * pointer to the struct net.
The access rules are simple:

 1. register the ops with register_pernet_gen_device to get
    the id of your private pointer
 2. call net_assign_generic() to put the private data on the
    struct net (most preferably this should be done in the
    ->init callback of the ops registered)
 3. do not store any private reference on the net_generic array;
 4. do not change this pointer while the net is alive;
 5. use the net_generic() to get the pointer.

When adding a new pointer, I copy the old array, replace it
with a new one and schedule the old for kfree after an RCU
grace period.

Since the net_generic explores the net->gen array inside rcu
read section and once set the net->gen->ptr[x] pointer never 
changes, this grants us a safe access to generic pointers.

Quoting Paul: "... RCU is protecting -only- the net_generic 
structure that net_generic() is traversing, and the [pointer]
returned by net_generic() is protected by a reference counter 
in the upper-level struct net."
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      dec827d1
  21. 14 4月, 2008 3 次提交
  23. 04 4月, 2008 1 次提交
  25. 01 4月, 2008 1 次提交