linux-kernel - Re: [PATCH] mm, compaction: Indicate when compaction is manually triggered by sysctl

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Message-ID: <CAHD1Q_wF6Mzf5JipXGZKvn2YDR+FQ6ePuKOe-1W-t_VapxMCxg@mail.gmail.com>
Date:   Fri, 8 May 2020 16:01:48 -0300
From:   Guilherme Piccoli <gpiccoli@...onical.com>
To:     David Rientjes <rientjes@...gle.com>
Cc:     "Guilherme G. Piccoli" <kernel@...ccoli.net>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Gavin Guo <gavin.guo@...onical.com>,
        Mel Gorman <mgorman@...hsingularity.net>
Subject: Re: [PATCH] mm, compaction: Indicate when compaction is manually
 triggered by sysctl

On Fri, May 8, 2020 at 3:31 PM David Rientjes <rientjes@...gle.com> wrote:
> It doesn't make sense because it's only being done here for the entire
> system, there are also per-node sysfs triggers so you could do something
> like iterate over the nodemask of all nodes with memory and trigger
> compaction manually and then nothing is emitted to the kernel log.
>
> There is new statsfs support that Red Hat is proposing that can be used
> for things like this.  It currently only supports KVM statistics but
> adding MM statistics is something that would be a natural extension and
> avoids polluting both the kernel log and /proc/vmstat.

Thanks for the review. Is this what you're talking about [0] ? Very interesting!

Also, I agree about the per-node compaction, it's a good point. But at
the same time, having the information on the number of manual
compaction triggered is interesting, at least for some users. What if
we add that as a per-node stat in zoneinfo?

Cheers,

Guilherme


[0] lore.kernel.org/kvm/20200427141816.16703-1-eesposit@...hat.com