linux-kernel - Re: Re: [PATCH v18 11/14] Documentation: Add documents for DAMON

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Date:   Mon, 27 Jul 2020 09:38:42 +0200
From:   SeongJae Park <sjpark@...zon.com>
To:     Greg Thelen <gthelen@...gle.com>
CC:     SeongJae Park <sjpark@...zon.com>, <akpm@...ux-foundation.org>,
        "SeongJae Park" <sjpark@...zon.de>, <Jonathan.Cameron@...wei.com>,
        <aarcange@...hat.com>, <acme@...nel.org>,
        <alexander.shishkin@...ux.intel.com>, <amit@...nel.org>,
        <benh@...nel.crashing.org>, <brendan.d.gregg@...il.com>,
        <brendanhiggins@...gle.com>, <cai@....pw>,
        <colin.king@...onical.com>, <corbet@....net>, <david@...hat.com>,
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        <yang.shi@...ux.alibaba.com>, <ying.huang@...el.com>,
        <linux-damon@...zon.com>, <linux-mm@...ck.org>,
        <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: Re: [PATCH v18 11/14] Documentation: Add documents for DAMON

On Mon, 27 Jul 2020 00:19:00 -0700 Greg Thelen <gthelen@...gle.com> wrote:

> SeongJae Park <sjpark@...zon.com> wrote:
> 
> > From: SeongJae Park <sjpark@...zon.de>
> >
> > This commit adds documents for DAMON under
> > `Documentation/admin-guide/mm/damon/` and `Documentation/vm/damon/`.
> >
> > Signed-off-by: SeongJae Park <sjpark@...zon.de>
> > ---
> >  Documentation/admin-guide/mm/damon/guide.rst | 157 ++++++++++
> >  Documentation/admin-guide/mm/damon/index.rst |  15 +
> >  Documentation/admin-guide/mm/damon/plans.rst |  29 ++
> >  Documentation/admin-guide/mm/damon/start.rst |  98 ++++++
> >  Documentation/admin-guide/mm/damon/usage.rst | 298 +++++++++++++++++++
> >  Documentation/admin-guide/mm/index.rst       |   1 +
> >  Documentation/vm/damon/api.rst               |  20 ++
> >  Documentation/vm/damon/eval.rst              | 222 ++++++++++++++
> >  Documentation/vm/damon/faq.rst               |  59 ++++
> >  Documentation/vm/damon/index.rst             |  32 ++
> >  Documentation/vm/damon/mechanisms.rst        | 165 ++++++++++
> >  Documentation/vm/index.rst                   |   1 +
> >  12 files changed, 1097 insertions(+)
> >  create mode 100644 Documentation/admin-guide/mm/damon/guide.rst
> >  create mode 100644 Documentation/admin-guide/mm/damon/index.rst
> >  create mode 100644 Documentation/admin-guide/mm/damon/plans.rst
> >  create mode 100644 Documentation/admin-guide/mm/damon/start.rst
> >  create mode 100644 Documentation/admin-guide/mm/damon/usage.rst
> >  create mode 100644 Documentation/vm/damon/api.rst
> >  create mode 100644 Documentation/vm/damon/eval.rst
> >  create mode 100644 Documentation/vm/damon/faq.rst
> >  create mode 100644 Documentation/vm/damon/index.rst
> >  create mode 100644 Documentation/vm/damon/mechanisms.rst
> >+
[...]
> > +===============
> > +Detailed Usages
> > +===============
> > +
> > +DAMON provides below three interfaces for different users.
> > +
> > +- *DAMON user space tool.*
> > +  This is for privileged people such as system administrators who want a
> > +  just-working human-friendly interface.  Using this, users can use the DAMON’s
> > +  major features in a human-friendly way.  It may not be highly tuned for
> > +  special cases, though.  It supports only virtual address spaces monitoring.
> > +- *debugfs interface.*
> > +  This is for privileged user space programmers who want more optimized use of
> > +  DAMON.  Using this, users can use DAMON’s major features by reading
> > +  from and writing to special debugfs files.  Therefore, you can write and use
> > +  your personalized DAMON debugfs wrapper programs that reads/writes the
> > +  debugfs files instead of you.  The DAMON user space tool is also a reference
> > +  implementation of such programs.  It supports only virtual address spaces
> > +  monitoring.
> > +- *Kernel Space Programming Interface.*
> > +  This is for kernel space programmers.  Using this, users can utilize every
> > +  feature of DAMON most flexibly and efficiently by writing kernel space
> > +  DAMON application programs for you.  You can even extend DAMON for various
> > +  address spaces.
> > +
> > +This document does not describe the kernel space programming interface in
> > +detail.  For that, please refer to the :doc:`/vm/damon/api`.
> > +
> > +
> > +DAMON User Sapce Tool
> 
> Space

Right, thanks!

> 
[...]
> > +
> > +Can 'idle pages tracking' or 'perf mem' substitute DAMON?
> > +=========================================================
> > +
> > +Idle page tracking is a low level primitive for access check of the physical
> > +address space.  'perf mem' is similar, though it can use sampling to minimize
> > +the overhead.  On the other hand, DAMON is a higher-level framework for the
> > +monitoring of various address spaces.  It is focused on memory management
> > +optimization and provides sophisticated accuracy/overhead handling mechanisms.
> > +Therefore, 'idle pages tracking' and 'perf mem' could provide a subset of
> > +DAMON's output, but cannot substitute DAMON.  Rather than that, thouse could be
> 
> those?

Good eye!  I will fix both in the next spin.


Thanks,
SeongJae Park