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Date:   Wed, 3 Jun 2020 12:27:05 -0700 (PDT)
From:   David Rientjes <rientjes@google.com>
To:     Vlastimil Babka <vbabka@suse.cz>
cc:     Gavin Guo <gavin.guo@canonical.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, akpm@linux-foundation.org,
        "Eric W . Biederman" <ebiederm@xmission.com>,
        Kees Cook <keescook@chromium.org>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Christian Brauner <christian.brauner@ubuntu.com>
Subject: Re: [PATCH] mm: thp: Add new kernel parameters
 transparent_hugepage_defrag/khugepaged_defrag
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On Wed, 3 Jun 2020, Vlastimil Babka wrote:

> > There is no way to set up the defrag options in boot time. And it's
> > useful to set it up by default instead of making it work by a
> > systemd/upstart service or put the command to set up defrag inside
> > /etc/rc.local.
> > 
> > Signed-off-by: Gavin Guo <gavin.guo@canonical.com>
> 
> Well, maybe isntead of adding these handlers, we could extend the new boot
> parameter sysctl support (handling procfs /proc/sys/) to sysfs (/sys) as well,
> as Eric already suggested? [1]
> 
> [1] https://lore.kernel.org/linux-api/87bloj2skm.fsf@x220.int.ebiederm.org/
> 

Fully agreed, I think the solution needs to be more generic since thp 
defrag isn't special here.  With the generic support to tune sysctls and 
sysfs tunables from the command line it seems like this patch would be 
redundant.