fib_flush walks the whole fib in a net_namespace and is called for
each net_device being closed or unregistered. This can be very expensive
when dealing with 100k or more routes in the fib and removal of a lot
of interfaces. These four patches deal with this issue by calling fib_flush
just once for each net namespace and introduce a new function arp_ifdown_all
that does a similar optimization for the neighbour table.
I got the following benchmark results on one of our switches.
Without this patch, deleting 1k interfaces with 100k routes in the fib held
the rtnl_lock for 13 seconds. With the patch, rtnl_lock hold time went down
to 5 seconds. The gain is even more pronounced with 512k routes in the FIB.
In this case, without the patch, rtnl_lock was held for 36 seconds and with
the patch it was held for 5.5 seconds.
Salam Noureddine (4):
net: add event_list to struct net and provide utility functions
net: dev: add batching to net_device notifiers
net: core: introduce neigh_ifdown_all for all down interfaces
net: fib: avoid calling fib_flush for each device when doing batch
close and unregister
include/linux/netdevice.h | 2 ++
include/net/arp.h | 1 +
include/net/neighbour.h | 1 +
include/net/net_namespace.h | 22 ++++++++++++++++++++++
include/net/netns/ipv4.h | 1 +
net/core/dev.c | 39 ++++++++++++++++++++++++++++++++++++---
net/core/neighbour.c | 38 +++++++++++++++++++++++++++++++-------
net/ipv4/arp.c | 4 ++++
net/ipv4/fib_frontend.c | 16 ++++++++++++++--
9 files changed, 112 insertions(+), 12 deletions(-)
--
1.8.1.4
