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Date: Wed, 29 Jul 2015 13:32:49 +0200
From: Petr Mladek <pmladek@suse.com>
Subject: Re: [RFC PATCH 07/14] mm/huge_page: Convert khugepaged() into
 kthread worker API
Message-ID: <20150729113249.GL2673@pathway.suse.cz>
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To: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>, Oleg Nesterov <oleg@redhat.com>, Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>, Steven Rostedt <rostedt@goodmis.org>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Josh Triplett <josh@joshtriplett.org>, Thomas Gleixner <tglx@linutronix.de>, Linus Torvalds <torvalds@linux-foundation.org>, Jiri Kosina <jkosina@suse.cz>, Borislav Petkov <bp@suse.de>, Michal Hocko <mhocko@suse.cz>, linux-mm@kvack.org, Vlastimil Babka <vbabka@suse.cz>, live-patching@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org

On Tue 2015-07-28 13:36:35, Tejun Heo wrote:
> Hello,
> 
> On Tue, Jul 28, 2015 at 04:39:24PM +0200, Petr Mladek wrote:
> > -static void khugepaged_wait_work(void)
> > +static void khugepaged_wait_func(struct kthread_work *dummy)
> >  {
> >  	if (khugepaged_has_work()) {
> >  		if (!khugepaged_scan_sleep_millisecs)
> > -			return;
> > +			goto out;
> >  
> >  		wait_event_freezable_timeout(khugepaged_wait,
> > -					     kthread_should_stop(),
> > +					     !khugepaged_enabled(),
> >  			msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
> > -		return;
> > +		goto out;
> >  	}
> >  
> >  	if (khugepaged_enabled())
> >  		wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
> > +
> > +out:
> > +	if (khugepaged_enabled())
> > +		queue_kthread_work(&khugepaged_worker,
> > +				   &khugepaged_do_scan_work);
> >  }
> 
> There gotta be a better way to do this.  It's outright weird to
> convert it over to work item based interface and then handle idle
> periods by injecting wait work items.  If there's an external event
> which wakes up the worker, convert that to a queueing event.  If it's
> a timed event, implement a delayed work and queue that with delay.

I am going to give it a try.

Best Regards,
Petr

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