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From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: akpm@linux-foundation.org, mhocko@suse.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, gorcunov@virtuozzo.com
Subject: Re: [PATCH] ksm: React on changing "sleep_millisecs" parameter faster
Date: Tue, 11 Dec 2018 13:03:46 +0300
Message-ID: <20181211100346.GE2342@uranus.lan> (raw)
In-Reply-To: <db19c148-b375-b6f2-dbf5-9e78f5e46c04@virtuozzo.com>

On Tue, Dec 11, 2018 at 12:23:11PM +0300, Kirill Tkhai wrote:
...
> > Kirill, can we rather reuse @ksm_thread variable from ksm_init
> > (by moving it to static file level variable).
> 
> I've considered using it, but this is not looks good for me.
> The problem is ksm thread may be parked, or it even may fail
> to start. But at the same time, parallel writes to "sleep_millisecs"
> are possible. There is a place for races, so to use the local
> variable in ksm_init() (like we have at the moment) looks better
> for me. At the patch the mutex protects against any races.
> 
> > Also wakening up
> > unconditionally on write looks somehow suspicious to me
> > though I don't have a precise argument against.
> 
> The conditional wait requires one more wait_queue. This is
> the thing I tried to avoid. But. I also had doubts about
> this, so you are already the second person, who worries :)
> It looks like we really need to change this.
> 
> How are you about something like the below?

I see. The code below looks a way better for me, thanks!

      reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-10 16:06 Kirill Tkhai
2018-12-10 20:10 ` Cyrill Gorcunov
2018-12-11  9:23   ` Kirill Tkhai
2018-12-11 10:03     ` Cyrill Gorcunov [this message]

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