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Date: Tue, 4 Aug 2009 14:59:35 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: ieidus@redhat.com, aarcange@redhat.com, riel@redhat.com, chrisw@redhat.com,
       nickpiggin@yahoo.com.au, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org
Subject: Re: [PATCH 5/12] ksm: keep quiet while list empty
Message-Id: <20090804145935.e258cd2f.akpm@linux-foundation.org>
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On Mon, 3 Aug 2009 13:14:03 +0100 (BST)
Hugh Dickins <hugh.dickins@tiscali.co.uk> wrote:

> +		if (ksmd_should_run()) {
>  			schedule_timeout_interruptible(
>  				msecs_to_jiffies(ksm_thread_sleep_millisecs));
>  		} else {
>  			wait_event_interruptible(ksm_thread_wait,
> -					(ksm_run & KSM_RUN_MERGE) ||
> -					kthread_should_stop());
> +				ksmd_should_run() || kthread_should_stop());
>  		}

Yields


		if (ksmd_should_run()) {
			schedule_timeout_interruptible(
				msecs_to_jiffies(ksm_thread_sleep_millisecs));
		} else {
			wait_event_interruptible(ksm_thread_wait,
				ksmd_should_run() || kthread_should_stop());
		}

can it be something like

		wait_event_interruptible_timeout(ksm_thread_wait,
			ksmd_should_run() || kthread_should_stop(),
			msecs_to_jiffies(ksm_thread_sleep_millisecs));

?

That would also reduce the latency in responding to kthread_should_stop().