selftests: vm: Try harder to allocate huge pages

If we need to increase the number of huge pages, drop caches first
to reduce fragmentation and then check that we actually allocated
as many as we wanted.  Retry once if that doesn't work.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>

diff --git a/tools/testing/selftests/vm/run_vmtests b/tools/testing/selftests/vm/run_vmtests
index 9179ce8df485d7b125b7e3619f7d82ee4df5ea64..97ed1b26293fdedfdc5f0ff2361b5ef25e604532 100755 (executable)
--- a/tools/testing/selftests/vm/run_vmtests
+++ b/tools/testing/selftests/vm/run_vmtests
@@ -20,13 +20,26 @@ done < /proc/meminfo
 if [ -n "$freepgs" ] && [ -n "$pgsize" ]; then
        nr_hugepgs=`cat /proc/sys/vm/nr_hugepages`
        needpgs=`expr $needmem / $pgsize`
-       if [ $freepgs -lt $needpgs ]; then
+       tries=2
+       while [ $tries -gt 0 ] && [ $freepgs -lt $needpgs ]; do
                lackpgs=$(( $needpgs - $freepgs ))
+               echo 3 > /proc/sys/vm/drop_caches
                echo $(( $lackpgs + $nr_hugepgs )) > /proc/sys/vm/nr_hugepages
                if [ $? -ne 0 ]; then
                        echo "Please run this test as root"
                        exit 1
                fi
+               while read name size unit; do
+                       if [ "$name" = "HugePages_Free:" ]; then
+                               freepgs=$size
+                       fi
+               done < /proc/meminfo
+               tries=$((tries - 1))
+       done
+       if [ $freepgs -lt $needpgs ]; then
+               printf "Not enough huge pages available (%d < %d)\n" \
+                      $freepgs $needpgs
+               exit 1
        fi
 else
        echo "no hugetlbfs support in kernel?"