linux/include
Eric Dumazet 34d101dd62 neigh: speedup neigh_hh_init()
When a new dst is used to send a frame, neigh_resolve_output() tries to
associate an struct hh_cache to this dst, calling neigh_hh_init() with
the neigh rwlock write locked.

Most of the time, hh_cache is already known and linked into neighbour,
so we find it and increment its refcount.

This patch changes the logic so that we call neigh_hh_init() with
neighbour lock read locked only, so that fast path can be run in
parallel by concurrent cpus.

This brings part of the speedup we got with commit c7d4426a98
(introduce DST_NOCACHE flag) for non cached dsts, even for cached ones,
removing one of the contention point that routers hit on multiqueue
enabled machines.

Further improvements would need to use a seqlock instead of an rwlock to
protect neigh->ha[], to not dirty neigh too often and remove two atomic
ops.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-10-11 09:16:57 -07:00
..
acpi ACPI: Fix typos 2010-09-28 21:38:19 -04:00
asm-generic gpio: doc updates 2010-09-09 18:57:24 -07:00
crypto
drm drm: Hold the mutex when dropping the last GEM reference (v2) 2010-10-01 21:08:45 +10:00
keys
linux neigh: speedup neigh_hh_init() 2010-10-11 09:16:57 -07:00
math-emu
media V4L/DVB: cx2341x: convert to the control framework 2010-08-08 23:43:05 -03:00
mtd mtd: Update copyright notices 2010-08-08 20:58:20 +01:00
net Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next-2.6 into for-davem 2010-10-08 15:39:28 -04:00
pcmcia
rdma
rxrpc
scsi scsi: use __uX types for headers exported to user space 2010-08-11 08:59:01 -07:00
sound ALSA: emu10k1 - delay the PCM interrupts (add pcm_irq_delay parameter) 2010-08-18 15:10:59 +02:00
trace Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-08-24 12:21:49 -07:00
video include: replace unifdef-y with header-y 2010-08-14 22:26:51 +02:00
xen xen: pvhvm: make it clearer that XEN_UNPLUG_* define bits in a bitfield 2010-08-23 12:01:35 +01:00
Kbuild