Messages in this thread | | | Date | Mon, 30 Jul 2018 17:26:41 -0700 | From | Jakub Kicinski <> | Subject | Re: [PATCH v3] Add BPF_SYNCHRONIZE_MAP_TO_MAP_REFERENCES bpf(2) command |
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On Mon, 30 Jul 2018 03:25:43 -0700, Daniel Colascione wrote: > On Mon, Jul 30, 2018 at 3:04 AM, Daniel Borkmann <daniel@iogearbox.net> wrote: > > Hmm, I don't think such UAPI as above is future-proof. In case we would want > > a similar mechanism in future for other maps, we would need a whole new bpf > > command or reuse BPF_SYNCHRONIZE_MAP_TO_MAP_REFERENCES as a workaround though > > the underlying map may not even be a map-to-map. Additionally, we don't have > > any map object at hand in the above, so we couldn't make any finer grained > > decisions either. Something like below would be more suitable and leaves room > > for extending this further in future. > > YAGNI. Your proposed mechanism doesn't add anything under the current > implementation.
FWIW in case of HW offload targeting a particular map may allow users to avoid a potentially slow sync with all the devices on the system.
> It's also not clear how a map-specific synchronization > command is supposed to work in cases where we swap multiple map > references. Do we synchronize_rcu multiple times? Why would we impose > that inefficiency just for the sake of some non-specific future > extensibility? Add some kind of batching layer? The current approach > works for the anticipated use cases. > > While my preference is not to talk about map-to-maps at all in the > user API and instead spec the thing as talking about map references in > general, I'd rather have something that talks about > references-to-maps-acquired-from-maps than this interface.
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