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* net: Add ->neigh_lookup() operation to dst_opsDavid S. Miller2011-07-181-0/+1
| | | | | | | | In the future dst entries will be neigh-less. In that environment we need to have an easy transition point for current users of dst->neighbour outside of the packet output fast path. Signed-off-by: David S. Miller <davem@davemloft.net>
* net: Implement read-only protection and COW'ing of metrics.David S. Miller2011-01-261-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Routing metrics are now copy-on-write. Initially a route entry points it's metrics at a read-only location. If a routing table entry exists, it will point there. Else it will point at the all zero metric place-holder called 'dst_default_metrics'. The writeability state of the metrics is stored in the low bits of the metrics pointer, we have two bits left to spare if we want to store more states. For the initial implementation, COW is implemented simply via kmalloc. However future enhancements will change this to place the writable metrics somewhere else, in order to increase sharing. Very likely this "somewhere else" will be the inetpeer cache. Note also that this means that metrics updates may transiently fail if we cannot COW the metrics successfully. But even by itself, this patch should decrease memory usage and increase cache locality especially for routing workloads. In those cases the read-only metric copies stay in place and never get written to. TCP workloads where metrics get updated, and those rare cases where PMTU triggers occur, will take a very slight performance hit. But that hit will be alleviated when the long-term writable metrics move to a more sharable location. Since the metrics storage went from a u32 array of RTAX_MAX entries to what is essentially a pointer, some retooling of the dst_entry layout was necessary. Most importantly, we need to preserve the alignment of the reference count so that it doesn't share cache lines with the read-mostly state, as per Eric Dumazet's alignment assertion checks. The only non-trivial bit here is the move of the 'flags' member into the writeable cacheline. This is OK since we are always accessing the flags around the same moment when we made a modification to the reference count. Signed-off-by: David S. Miller <davem@davemloft.net>
* net: Abstract default MTU metric calculation behind an accessor.David S. Miller2010-12-141-0/+1
| | | | | | | | | | | Like RTAX_ADVMSS, make the default calculation go through a dst_ops method rather than caching the computation in the routing cache entries. Now dst metrics are pretty much left as-is when new entries are created, thus optimizing metric sharing becomes a real possibility. Signed-off-by: David S. Miller <davem@davemloft.net>
* net: Abstract default ADVMSS behind an accessor.David S. Miller2010-12-131-0/+1
| | | | | | | | | | | | | | | | | | Make all RTAX_ADVMSS metric accesses go through a new helper function, dst_metric_advmss(). Leave the actual default metric as "zero" in the real metric slot, and compute the actual default value dynamically via a new dst_ops AF specific callback. For stacked IPSEC routes, we use the advmss of the path which preserves existing behavior. Unlike ipv4/ipv6, DecNET ties the advmss to the mtu and thus updates advmss on pmtu updates. This inconsistency in advmss handling results in more raw metric accesses than I wish we ended up with. Signed-off-by: David S. Miller <davem@davemloft.net>
* net dst: need linux/cache.h for ____cacheline_aligned_in_smp.Paul Mundt2010-11-071-0/+1
| | | | | | | | | | | | | | | | | | | | | | | Presently the b43legacy build fails on an sh randconfig: In file included from include/net/dst.h:12, from drivers/net/wireless/b43legacy/xmit.c:32: include/net/dst_ops.h:28: error: expected ':', ',', ';', '}' or '__attribute__' before '____cacheline_aligned_in_smp' include/net/dst_ops.h: In function 'dst_entries_get_fast': include/net/dst_ops.h:33: error: 'struct dst_ops' has no member named 'pcpuc_entries' include/net/dst_ops.h: In function 'dst_entries_get_slow': include/net/dst_ops.h:41: error: 'struct dst_ops' has no member named 'pcpuc_entries' include/net/dst_ops.h: In function 'dst_entries_add': include/net/dst_ops.h:49: error: 'struct dst_ops' has no member named 'pcpuc_entries' include/net/dst_ops.h: In function 'dst_entries_init': include/net/dst_ops.h:55: error: 'struct dst_ops' has no member named 'pcpuc_entries' include/net/dst_ops.h: In function 'dst_entries_destroy': include/net/dst_ops.h:60: error: 'struct dst_ops' has no member named 'pcpuc_entries' make[5]: *** [drivers/net/wireless/b43legacy/xmit.o] Error 1 make[5]: *** Waiting for unfinished jobs.... Signed-off-by: Paul Mundt <lethal@linux-sh.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* net dst: use a percpu_counter to track entriesEric Dumazet2010-10-111-1/+36
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | struct dst_ops tracks number of allocated dst in an atomic_t field, subject to high cache line contention in stress workload. Switch to a percpu_counter, to reduce number of time we need to dirty a central location. Place it on a separate cache line to avoid dirtying read only fields. Stress test : (Sending 160.000.000 UDP frames, IP route cache disabled, dual E5540 @2.53GHz, 32bit kernel, FIB_TRIE, SLUB/NUMA) Before: real 0m51.179s user 0m15.329s sys 10m15.942s After: real 0m45.570s user 0m15.525s sys 9m56.669s With a small reordering of struct neighbour fields, subject of a following patch, (to separate refcnt from other read mostly fields) real 0m41.841s user 0m15.261s sys 8m45.949s Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* netns: embed ip6_dst_ops directlyAlexey Dobriyan2009-09-011-0/+28
struct net::ipv6.ip6_dst_ops is separatedly dynamically allocated, but there is no fundamental reason for it. Embed it directly into struct netns_ipv6. For that: * move struct dst_ops into separate header to fix circular dependencies I honestly tried not to, it's pretty impossible to do other way * drop dynamical allocation, allocate together with netns For a change, remove struct dst_ops::dst_net, it's deducible by using container_of() given dst_ops pointer. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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