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ee8f97efa7
Another thing making netns dismantles potentially very slow is located
in gro_cells_destroy(),
whenever cleanup_net() has to remove a device using gro_cells framework.
RTNL is not held at this stage, so synchronize_net()
is calling synchronize_rcu():
netdev_run_todo()
ip_tunnel_dev_free()
gro_cells_destroy()
synchronize_net()
synchronize_rcu() // Ouch.
This patch uses call_rcu(), and gave me a 25x performance improvement
in my tests.
cleanup_net() is no longer blocked ~10 ms per synchronize_rcu()
call.
In the case we could not allocate the memory needed to queue the
deferred free, use synchronize_rcu_expedited()
v2: made percpu_free_defer_callback() static
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20220220041155.607637-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>