Messages in this thread | | | Date | Wed, 5 Aug 2009 12:54:49 +0100 (BST) | From | Hugh Dickins <> | Subject | Re: [PATCH 5/12] ksm: keep quiet while list empty |
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On Tue, 4 Aug 2009, Andrew Morton wrote: > 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
(Phew, for a moment I thought you were asking us to use yield() here.)
> > > 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)); > > ?
I'd be glad to simplify what we have there, but I think your proposal ends up doing exactly what we're trying to avoid, doesn't it? Won't it briefly wake up ksmd every ksm_thread_sleep_millisecs, even when there's nothing for it to do?
> > That would also reduce the latency in responding to kthread_should_stop().
That's not a high priority consideration. So far as I can tell, the only use for that test is at startup, if the sysfs_create_group mysteriously fails. It's mostly a leftover from when you could have CONFIG_KSM=m:
I did wonder whether to go back and add some SLAB_PANICs etc now, but in the end I was either too lazy or too deferential to Izik's fine error handling (you choose which to believe: both, actually).
Hugh
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