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From:   Suren Baghdasaryan <surenb@google.com>
Date:   Thu, 1 Sep 2022 08:39:48 -0700
Message-ID: <CAJuCfpEgWx4mmiSCvcMOF0+Luyw1w-hVyLV-cvhbxnwsN6qg0g@mail.gmail.com>
Subject: Re: [RFC PATCH 00/30] Code tagging framework and applications
To:     David Hildenbrand <david@redhat.com>
Cc:     Kent Overstreet <kent.overstreet@linux.dev>,
        Michal Hocko <mhocko@suse.com>, Mel Gorman <mgorman@suse.de>,
        Peter Zijlstra <peterz@infradead.org>,
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On Thu, Sep 1, 2022 at 8:07 AM David Hildenbrand <david@redhat.com> wrote:
>
> On 01.09.22 16:23, Kent Overstreet wrote:
> > On Thu, Sep 01, 2022 at 10:05:03AM +0200, David Hildenbrand wrote:
> >> On 31.08.22 21:01, Kent Overstreet wrote:
> >>> On Wed, Aug 31, 2022 at 12:47:32PM +0200, Michal Hocko wrote:
> >>>> On Wed 31-08-22 11:19:48, Mel Gorman wrote:
> >>>>> Whatever asking for an explanation as to why equivalent functionality
> >>>>> cannot not be created from ftrace/kprobe/eBPF/whatever is reasonable.
> >>>>
> >>>> Fully agreed and this is especially true for a change this size
> >>>> 77 files changed, 3406 insertions(+), 703 deletions(-)
> >>>
> >>> In the case of memory allocation accounting, you flat cannot do this with ftrace
> >>> - you could maybe do a janky version that isn't fully accurate, much slower,
> >>> more complicated for the developer to understand and debug and more complicated
> >>> for the end user.
> >>>
> >>> But please, I invite anyone who's actually been doing this with ftrace to
> >>> demonstrate otherwise.
> >>>
> >>> Ftrace just isn't the right tool for the job here - we're talking about adding
> >>> per callsite accounting to some of the fastest fast paths in the kernel.
> >>>
> >>> And the size of the changes for memory allocation accounting are much more
> >>> reasonable:
> >>>  33 files changed, 623 insertions(+), 99 deletions(-)
> >>>
> >>> The code tagging library should exist anyways, it's been open coded half a dozen
> >>> times in the kernel already.
> >>
> >> Hi Kent,
> >>
> >> independent of the other discussions, if it's open coded already, does
> >> it make sense to factor that already-open-coded part out independently
> >> of the remainder of the full series here?
> >
> > It's discussed in the cover letter, that is exactly how the patch series is
> > structured.
>
> Skimming over the patches (that I was CCed on) and skimming over the
> cover letter, I got the impression that everything after patch 7 is
> introducing something new instead of refactoring something out.

Hi David,
Yes, you are right, the RFC does incorporate lots of parts which can
be considered separately. They are sent together to present the
overall scope of the proposal but I do intend to send them separately
once we decide if it's worth working on.
Thanks,
Suren.

>
> >
> >> [I didn't immediately spot if this series also attempts already to
> >> replace that open-coded part]
> >
> > Uh huh.
> >
> > Honestly, some days it feels like lkml is just as bad as slashdot, with people
> > wanting to get in their two cents without actually reading...
>
> ... and of course you had to reply like that. I should just have learned
> from my last upstream experience with you and kept you on my spam list.
>
> Thanks, bye
>
> --
> Thanks,
>
> David / dhildenb
>