On Wed, Mar 3, 2010 at 9:14 AM, David Rientjes <rientjes@xxxxxxxxxx> wrote:
> On Tue, 2 Mar 2010, Minchan Kim wrote:
>
>> > Why do you reset nice value which set by set_kswapd_nice?
>>
>> My point is that you reset nice value(which is boosted at wakeup_kswapd) to 0
>> before calling balance_pgdat. It means kswapd could be rescheduled by nice 0
>> before really reclaim happens by balance_pgdat.
>
> wakeup_kswapd() wakes up kswapd at the finish_wait() point so that it has
> the nice value set by set_kswapd_nice() when it calls balance_pgdat(),
> loops, and then sets it back to the default nice level of 0.
I can't understand your point.
Now kswapd is working following as.
for (; ;) {
prepare_to_wait();
if ( ... ) {
...
...
schedule() < --- wakeup point
...
set_user_nice(tsk, 0); <-- You reset nice value to zero.
order = pgdata->kswapd_max_order;
}
finish_wait();
balance_pgdat(); << before entering balance_pgdat, the nice vaule
will be invalidated.
}
As above code, wakeup_kswapd() wakes up kswapd at not finish_wait but
next line of schedule(). So I think nice vaule promoted by
wakeup_kswapd would be invalidated.
--
Kind regards,
Minchan Kim
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