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From:   Suren Baghdasaryan <surenb@google.com>
Date:   Fri, 28 Apr 2023 09:14:12 -0700
Message-ID: <CAJuCfpHouhrEtomhPe2sf+p0oG4pGFKb3xidhOXP6BN-PydY-Q@mail.gmail.com>
Subject: Re: [GIT PULL] MM updates for 6.4-rc1
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        mm-commits@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Lorenzo Stoakes <lstoakes@gmail.com>,
        Vlastimil Babka <vbabka@suse.cz>
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On Fri, Apr 28, 2023 at 9:08=E2=80=AFAM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Fri, Apr 28, 2023 at 9:03=E2=80=AFAM Suren Baghdasaryan <surenb@google=
.com> wrote:
> >
> > I wanted these stats enabled by default to be able to identify
> > possible pathological cases and to also let users disable them if they
> > can't tolerate even a small overhead in the pagefault path. Should I
> > document this reasoning for the config option?
>
> You should document what the stats actually count (at a high enough
> level for a user to understand), and why anybody would want to keep
> them on.
>
> Honestly, 99% of the time, these are things that *developers* think
> they might want, but that nobody else will ever ever use.
>
> Really, ask yourself if a normal user would ever look at them?
>
> Now, ask yourself whether this might be something that a cloud
> provider would want to look at to gather statistics.
>
> And if it's the latter case, then it should be "default n", because
> the default should be for the people who DO NOT KNOW, AND DO NOT CARE.
>
> The cloud provider will be using a custom config anyway. The default
> is irrelevant for that use. The use that *matters* is literally the
> clueless end user who I bet will never look at these numbers, and will
> never be asked for them.

Ok, sounds like this should be 'default n'. I'll prepare a patch. Thanks!

>
>                Linus