Re: [PATCH v2 0/4] Static calls

From: Edward Cree
Date: Wed Dec 12 2018 - 12:11:09 EST

On 12/12/18 05:59, Nadav Amit wrote:
> Thanks for ccâing me. (I didnât know about the other patch-sets.)
Well in my case, that's because I haven't posted any yet. (Will follow up
Âshortly with what I currently have, though it's not pretty.)

Looking at your patches, it seems you've got a much more developed learning
Âmechanism. Mine on the other hand is brutally simple but runs continuously
Â(i.e. after we patch we immediately enter the next 'relearning' phase);
Âsince it never does anything but prod a handful of percpu variables, this
Âshouldn't be too costly.

Also, you've got the macrology for making all indirect calls use this,
Âwhereas at present I just have an open-coded instance on a single call site
Â(I went with deliver_skb in the networking stack).

So I think where we probably want to go from here is:
Â1) get Josh's static_calls in. AIUI Linus seems to prefer the out-of-line
ÂÂÂ approach; I'd say ditch the inline version (at least for now).
Â2) build a relpolines patch series that uses
ÂÂ i) static_calls for the text-patching part
 ii) as much of Nadav's macrology as is applicable
Âiii) either my or Nadav's learning mechanism; we can experiment with both,
ÂÂÂÂÂ bikeshed it incessantly etc.

Seem reasonable?