* [PATCH net] netns: add schedule point in ops_exit_list()
@ 2022-01-18 11:43 Eric Dumazet
2022-01-18 13:50 ` patchwork-bot+netdevbpf
0 siblings, 1 reply; 2+ messages in thread
From: Eric Dumazet @ 2022-01-18 11:43 UTC (permalink / raw)
To: David S . Miller, Jakub Kicinski
Cc: netdev, Eric Dumazet, Eric Dumazet, Eric W . Biederman
From: Eric Dumazet <edumazet@google.com>
When under stress, cleanup_net() can have to dismantle
netns in big numbers. ops_exit_list() currently calls
many helpers [1] that have no schedule point, and we can
end up with soft lockups, particularly on hosts
with many cpus.
Even for moderate amount of netns processed by cleanup_net()
this patch avoids latency spikes.
[1] Some of these helpers like fib_sync_up() and fib_sync_down_dev()
are very slow because net/ipv4/fib_semantics.c uses host-wide hash tables,
and ifindex is used as the only input of two hash functions.
ifindexes tend to be the same for all netns (lo.ifindex==1 per instance)
This will be fixed in a separate patch.
Fixes: 72ad937abd0a ("net: Add support for batching network namespace cleanups")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
---
net/core/net_namespace.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 9b7171c40434985b869c1477975fc75447d78c3b..a5b5bb99c64462dac2513f7b3e28cb0763844c21 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -164,8 +164,10 @@ static void ops_exit_list(const struct pernet_operations *ops,
{
struct net *net;
if (ops->exit) {
- list_for_each_entry(net, net_exit_list, exit_list)
+ list_for_each_entry(net, net_exit_list, exit_list) {
ops->exit(net);
+ cond_resched();
+ }
}
if (ops->exit_batch)
ops->exit_batch(net_exit_list);
--
2.34.1.703.g22d0c6ccf7-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net] netns: add schedule point in ops_exit_list()
2022-01-18 11:43 [PATCH net] netns: add schedule point in ops_exit_list() Eric Dumazet
@ 2022-01-18 13:50 ` patchwork-bot+netdevbpf
0 siblings, 0 replies; 2+ messages in thread
From: patchwork-bot+netdevbpf @ 2022-01-18 13:50 UTC (permalink / raw)
To: Eric Dumazet; +Cc: davem, kuba, netdev, edumazet, ebiederm
Hello:
This patch was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:
On Tue, 18 Jan 2022 03:43:40 -0800 you wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> When under stress, cleanup_net() can have to dismantle
> netns in big numbers. ops_exit_list() currently calls
> many helpers [1] that have no schedule point, and we can
> end up with soft lockups, particularly on hosts
> with many cpus.
>
> [...]
Here is the summary with links:
- [net] netns: add schedule point in ops_exit_list()
https://git.kernel.org/netdev/net/c/2836615aa22d
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
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^ permalink raw reply [flat|nested] 2+ messages in thread
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2022-01-18 11:43 [PATCH net] netns: add schedule point in ops_exit_list() Eric Dumazet
2022-01-18 13:50 ` patchwork-bot+netdevbpf
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