Re: [PATCH] ksm: React on changing "sleep_millisecs" parameter faster

[Cyrill Gorcunov <gorcunov@gmail.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!