move_pages12: Make sure hugepages are available
This commit makes sure that enough huge pages are available on each node prior
to the test.
One problem we had is that there has to be at least four huge pages
available in the per-node pools even though we only allocate two. One of
the possibilities is that when we are moving pages back and forth
between the nodes there may be some overlap when huge page is allocated
on a node but the two huge pages there, that are about to be moved, are
still there or at least accounted for. Hence we have to make sure that
at least four huge pages are available prior to the test.
The second problem is that huge page pools are limited by several files in the
virtual filesystem. There is global knob for controlling the huge page pool
size in /proc, then there are per-node knobs in /sys. The value written to the
global knob is distributed evenly between the per-node knobs, hence on two node
machine writing 8 to the global knob is sufficient to make sure there is enough
huge pages for the test. But that does not work if the machine has three or
more nodes. Hence this patch tries to adjust per-node pools on the nodes
selected for the test and only if that is not possible we adjust the global
knob and then make sure that expected number of huge pages could be allocated
on each node.
Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Jan Stancek <jstancek@redhat.com>
1 file changed