On Wed, Feb 15, 2017 at 7:18 PM, David Ahern <d...@cumulusnetworks.com> wrote: > On 2/15/17 8:08 PM, Eric W. Biederman wrote: >> David Ahern <d...@cumulusnetworks.com> writes: >> >>> On 2/14/17 12:21 AM, Eric W. Biederman wrote: >>>>> in cases where bpf programs are looking at sockets and packets >>>>> that belong to different netns, it could be useful to get an id >>>>> that uniquely identify a netns within the whole system. >>>> It could be useful but there is no unique namespace id. >>>> >>> >>> Have you given thought to a unique namespace id? Networking tracepoints >>> for example could really benefit from a unique id. >> >> An id from the perspective of a process in the initial instance of every >> namespace is certainly possible. >> >> A truly unique id is just not maintainable. Think of the question how >> do you assign every device in the world a rguaranteed unique ip address >> without coordination, that is routable. It is essentially the same >> problem. >> >> AKA it is theoretically possible and very expensive. It is much easier >> and much more maintainable for identifiers to have scope and only be >> unique within that scope. > > > I don't mean unique in the entire world, I mean unique within a single > system. > > Tracepoints are code based and have global scope. I would like to be > able to correlate, for example, FIB lookups within a single network > namespace. Having an id that I could filter on when collecting or match > when dumping them goes a long way.
Why wouldn't an id relative to your logging program work? Global ids are problematic because they are incompatible with tools like CRIU. -- Andy Lutomirski AMA Capital Management, LLC
