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

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Date:   Mon,  7 Feb 2022 08:16:25 +0000
From:   SeongJae Park <sj@...nel.org>
To:     Pedro Gomes <pedrodemargomes@...il.com>
Cc:     SeongJae Park <sj@...nel.org>,
        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 Fri, 4 Feb 2022 12:11:44 -0300 Pedro Gomes <pedrodemargomes@...il.com> wrote:

> 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.

Thanks!

> 
> > > 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?

Yes, that idea makes sense to me :)


Thanks,
SJ

> 
> 
> -- 
> Atenciosamente,
> Pedro Demarchi Gomes.