Comment 10 for bug 2025030

@Alex Murray <email address hidden> github action is good idea to
optimise on the interface level and PR I open is trying to do that (though
I have done it manually)
But this has limitation as this optimisation can be done only per interface.
Preprocessing the full profile has the potential to optimise
cross-interfaces when multiple interfaces could define the same expression.
But one can argue that apparmor_parser should have this as the first step
before even parsing the profile, dummy dedupe and simplification of the
profile before building the tree.
it seems a lot cheaper as pre-processing step

On Tue, 4 Jul 2023 at 04:25, John Johansen <email address hidden>
wrote:

> so I think this is largely because the apparmor version snap is using is
> not running rule deduplication on mount rules.
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/2025030
>
> Title:
> apparmor_parser -O no-expr-simplify problematic
>
> Status in snapd:
> In Progress
>
> Bug description:
> There was a recent issue with a core refresh that caused breakage.
> Upon further investigation it turns out that the apparmor_parser uses
> an substantial of memory.
>
> Upon some more investigation it turns out that that -O no-expr-
> simplify makes both time to compile and memory usage increase 10x.
> Tested with 22.04 but I see the same ballpark results with 16.04:
>
> $ /usr/bin/time --verbose apparmor_parser -S
> 2.59/profiles/snap.screenly-client.command-executor > /dev/null
> Command being timed: "apparmor_parser -S
> 2.59/profiles/snap.screenly-client.command-executor"
> User time (seconds): 4.32
> Maximum resident set size (kbytes): 117392
>
> $ /usr/bin/time --verbose apparmor_parser -O no-expr-simplify -S
> 2.59/profiles/snap.screenly-client.command-executor > /dev/null
> Command being timed: "apparmor_parser -O no-expr-simplify -S
> 2.59/profiles/snap.screenly-client.command-executor"
> User time (seconds): 40.64
> Maximum resident set size (kbytes): 1015816
>
> Profile is attached.
>
>
> It seems like we seriously need to consider dropping "-O
> no-expr-simplify".
>
> For context:
> https://bugs.launchpad.net/ubuntu-rtm/+source/apparmor/+bug/1383858
> is why it was added in the first place
>
> And some recent work to make things faster:
> https://gitlab.com/apparmor/apparmor/-/merge_requests/711
>
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>