Re: [iproute PATCHv2 0/2] Netns performance improvements

Stephen Hemminger [off-list ref] writes:

On Tue,  5 Jul 2016 16:51:18 +0200
Phil Sutter [off-list ref] wrote:

quoted

Stress-testing OpenStack Neutron revealed poor performance of 'ip netns'
when dealing with a high amount of namespaces. The cause of this lies in
the combination of how iproute2 mounts NETNS_RUN_DIR and the netns files
therein and the fact that systemd makes all mount points of the system
shared.

Changes since v1:
- Added Suggested-by tag to patches.

Phil Sutter (2):
  ipnetns: Move NETNS_RUN_DIR into it's own propagation group
  ipnetns: Make netns mount points private

 ip/ipnetns.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

I want an ack for Eric on this, it seems a little risky

If I have read the tea leaves properly the first patch is fighting
a system configuration of "mount --rbind /run /var/run" which seems
inappropriate.  A symlink is likely a better fix.

The effect of the second patch is probably better had by performing the
optimization in the kernel, so everyone gets the benefit.

I am persuadable to change this behavior.  But if all we are doing is
optimization and not intentionally changing the semantics there appear
to be better places for the optimizations to happen.

Eric