linux-kernel - Re: [PATCH] mm/damon: Add option to monitor only writes

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Message-ID: <CACpbsfZN2fExaTReJG1anDQjCd3i24_0wG-oU42dSHD5bAon7A@mail.gmail.com>
Date:   Fri, 4 Feb 2022 12:11:44 -0300
From:   Pedro Gomes <pedrodemargomes@...il.com>
To:     SeongJae Park <sj@...nel.org>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/damon: Add option to monitor only writes

On Thu, Feb 3, 2022 at 10:39 AM SeongJae Park <sj@...nel.org> wrote:

> I think this would be better to be implemented as another monitoring primitive
> based on the virtual address space monitoring primitives, e.g., vaddr-writes?
> Then the implementation would be simpler and changes to other files will be
> minimized.  For the user space interface, we could use a prefix to target_ids
> debugfs file.  For example,
>
>     # echo "vaddr-writes $(pidof workload)" > $debugfs/damon/target_ids

I will do that.

> > This patch also adds the actions mergeable and unmergeable to damos schemes.
> > These actions are used by KSM as explained in [1].
>
> Please do that in a separate patch, and also update the document
> (Documentation/admin-guide/mm/damon/usage.rst).  And, what's the expected usage
> of the action and benefits?

The idea is to use this action to all areas that are not written too frequently,
this way KSM can save more memory without too much overhead.
But I have to test it better and collect some data to see if it really
makes sense,
perhaps it is better to leave this patch for later.
I would like to know your opinion on this, do you think it makes sense?


-- 
Atenciosamente,
Pedro Demarchi Gomes.