On Wed, Apr 3, 2024 at 4:15 PM Brian Haley via discuss <
ovs-discuss@openvswitch.org> wrote:
> Hi,
>
> I recently have been seeing issues in a large environment where the
> listen backlog of ovsdb-server, both NB and SB, is getting over-flowed,
> for example:
>
> 17842 times the listen queue of a socket overflowed
> 17842 SYNs to LISTEN sockets dropped
>
> There is more on NB than SB, but I was surprised to see any. I can only
> guess at the moment it is happening when the leader changes and hundreds
> of nodes try and reconnect.
>
> Looking at their sockets I can see the backlog is only set to 10:
>
> $ ss -ltm | grep 664
> LISTEN 0 10 0.0.0.0:6641 0.0.0.0:*
> LISTEN 0 10 0.0.0.0:6642 0.0.0.0:*
>
> Digging into the code, there is only two places where listen() is
> called, one being inet_open_passive():
>
> /* Listen. */
> if (style == SOCK_STREAM && listen(fd, 10) < 0) {
> error = sock_errno();
> VLOG_ERR("%s: listen: %s", target, sock_strerror(error));
> goto error;
> }
>
> There is no way to config around this to even test if increasing would
> help in a running environment.
>
> So my question is two-fold:
>
> 1) Should this be increased? 128, 256, 1024? I can send a patch.
>
> 2) Should this be configurable?
>
> Has anyone else seen this?
>
Yes, I've seen it, though I was focusing on AF_UNIX behavior. You may want
to check this series:
https://patchwork.ozlabs.org/project/openvswitch/list/?series=382739&state=%2A&archive=both
Specifically, it includes a patch to bump the value for INET sockets to 64:
https://patchwork.ozlabs.org/project/openvswitch/patch/20231118010703.4154866-2-ihrac...@redhat.com/
The series includes a number of other fixes related to unixctl socket
handling; I am planning to revive this series in next few months, but
perhaps we could untangle this bump limit patch from the series and merge
it independently.
As to the question of potential configurability, I have nothing to
contribute.
Ihar
>
> Thanks for any thoughts.
>
> -Brian
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> disc...@openvswitch.org
> https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
>
>
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