Messages in this thread | | | Subject | Re: [PATCH net-next 0/5] rtnetlink: add IFA_IF_NETNSID for RTM_GETADDR | From | Kirill Tkhai <> | Date | Mon, 3 Sep 2018 17:53:19 +0300 |
| |
On 03.09.2018 16:50, Jiri Benc wrote: > On Mon, 3 Sep 2018 16:41:45 +0300, Kirill Tkhai wrote: >> But this is a synthetic test, while I asked about real workflow. >> Is this real problem for lxd, and there is observed performance >> decrease? > > It's actually not as much a performance problem but rather the only way > to get the data in some situations. Namely, when you have only netnsid. > This happens e.g. when you want to query a veth peer in another netns. > > setns() requires a file descriptor which you don't have. Nor there is > a way to convert netnsid to a fd. > > While developing the IFLA_IF_NETNSID patch, I was first thinking about > implementing an API doing the conversion. The problem is there's no > good place to put this into. It can't be done over netlink: netlink is > unreliable and you can't have the kernel open a fd for you and lose it. > There's no ioctl to use. So we'd be left with a procfs/sysfs or a > syscall. > > Using netnsid to refer to the target netns seems to be a nice solution - > after all, netnsid is the identifier to use in netlink.
Ok, I have no objections, just mentioning that generic problem.
Thanks, Kirill
| |