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Message-ID: <167751.1628789293@turing-police>
Date:   Thu, 12 Aug 2021 13:28:13 -0400
From:   "Valdis Klētnieks" <valdis.kletnieks@...edu>
To:     SeongJae Park <sj38.park@...il.com>
Cc:     SeongJae Park <sjpark@...zon.de>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org

On Thu, 12 Aug 2021 09:42:40 -0000, SeongJae Park said:

> -         This feature adds PG_idle and PG_young flags in 'struct page'.  PTE
> -         Accessed bit writers can set the state of the bit in the flags to let
> -         other PTE Accessed bit readers don't disturbed.
> +         This feature adds 'PG_idle' and 'PG_young' flags in 'struct page'.
> +         PTE Accessed bit writers can save the state of the bit in the flags
> +         to let other PTE Accessed bit readers don't get disturbed.

Well, better English would be "to let other ... not be disturbed'.

But I was rather hoping for an explanation of what "don't get disturbed" actually means.

If you are "save the state of the bit", are you saving the *previous* value (in
which case, other readers of the bit may or may not encounter changed behavior),
or are you saving a shadow copy that may have different values than the original
flags, and only used by a few routines?

Or are you creating two new status flags that are only used by several
optimized/fastpath routines and ignored by the other readers of the various
flag bits?

So a better description would be something like

This feature adds two new status bits PG_idle and PG_young to 'struct page'.
This allows passing additional information to certain users of PTE Accessed so
they can use an optimized codepath bypassing expensive checks for certain
common cases.

or "so they can provide <describe different behavior>"

or whatever this option is doing.

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