[LTP] [RFC] [PATCH] move_pages12: Allocate and free hugepages prior the test

Jan Stancek
2017-05-11T12:50:49Z

----- Original Message -----
> Hi!
> > > Well that is a few forks away after the failure, if the race window is
> > > small enough we will never see the real value but maybe doing open() and
> > > read() directly would show us different values.
> >
> > For free/reserved, sure. But is the number of reserved huge pages on
> > each node going to change over time?
>
> Of course I was speaking about the number of currently free huge pages.
> The pool limit will not change unless something from userspace writes to
> the sysfs file...
>
> > ---
> >
> > I was running with 20+20 huge pages over night and it hasn't failed
> > single time. So I'm thinking we allocate 3+3 or 4+4 to avoid any
> > issues related to lazy/deffered updates.
>
> But we have to lift the per node limits as well, right?

Sorry, what I meant by 'allocate' was configuring per node limits.
I was using your patch as-is, with 2 huge pages allocated/touched
on each node.

>
> So what about lifting the per node limit to something as 20 and then try
> to allocate 4 hugepages on each node prior the test?

per node limit 8 and allocate 4 hugepages on each? What worries
me are architectures, where default huge page is very large
(e.g. 512M on aarch64).

Regards,
Jan