From 002d8a1a6c11b9b2a8ac615095589111dd52749b Mon Sep 17 00:00:00 2001 From: Andrey Vagin Date: Mon, 24 Oct 2016 19:09:53 -0700 Subject: [PATCH] net: skip genenerating uevents for network namespaces that are exiting No one can see these events, because a network namespace can not be destroyed, if it has sockets. Unlike other devices, uevent-s for network devices are generated only inside their network namespaces. They are filtered in kobj_bcast_filter() My experiments shows that net namespaces are destroyed more 30% faster with this optimization. Here is a perf output for destroying network namespaces without this patch. - 94.76% 0.02% kworker/u48:1 [kernel.kallsyms] [k] cleanup_net - 94.74% cleanup_net - 94.64% ops_exit_list.isra.4 - 41.61% default_device_exit_batch - 41.47% unregister_netdevice_many - rollback_registered_many - 40.36% netdev_unregister_kobject - 14.55% device_del + 13.71% kobject_uevent - 13.04% netdev_queue_update_kobjects + 12.96% kobject_put - 12.72% net_rx_queue_update_kobjects kobject_put - kobject_release + 12.69% kobject_uevent + 0.80% call_netdevice_notifiers_info + 19.57% nfsd_exit_net + 11.15% tcp_net_metrics_exit + 8.25% rpcsec_gss_exit_net It's very critical to optimize the exit path for network namespaces, because they are destroyed under net_mutex and many namespaces can be destroyed for one iteration. v2: use dev_set_uevent_suppress() Cc: Cong Wang Cc: "David S. Miller" Cc: Eric W. Biederman Signed-off-by: Andrei Vagin Signed-off-by: David S. Miller --- net/core/net-sysfs.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 6e4f34721080..d4fe28606ff5 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -950,10 +950,13 @@ net_rx_queue_update_kobjects(struct net_device *dev, int old_num, int new_num) } while (--i >= new_num) { + struct kobject *kobj = &dev->_rx[i].kobj; + + if (!list_empty(&dev_net(dev)->exit_list)) + kobj->uevent_suppress = 1; if (dev->sysfs_rx_queue_group) - sysfs_remove_group(&dev->_rx[i].kobj, - dev->sysfs_rx_queue_group); - kobject_put(&dev->_rx[i].kobj); + sysfs_remove_group(kobj, dev->sysfs_rx_queue_group); + kobject_put(kobj); } return error; @@ -1340,6 +1343,8 @@ netdev_queue_update_kobjects(struct net_device *dev, int old_num, int new_num) while (--i >= new_num) { struct netdev_queue *queue = dev->_tx + i; + if (!list_empty(&dev_net(dev)->exit_list)) + queue->kobj.uevent_suppress = 1; #ifdef CONFIG_BQL sysfs_remove_group(&queue->kobj, &dql_group); #endif @@ -1525,6 +1530,9 @@ void netdev_unregister_kobject(struct net_device *ndev) { struct device *dev = &(ndev->dev); + if (!list_empty(&dev_net(ndev)->exit_list)) + dev_set_uevent_suppress(dev, 1); + kobject_get(&dev->kobj); remove_queue_kobjects(ndev); -- 2.20.1