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>
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>
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>
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>
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>
