How to calculate the size of hugepage used by a specific process/application on RHEL/CentOS 6,7?

Updated: 28 September 2026 · Applies to: Ubuntu 24.04, Debian 12, AlmaLinux 9 and Rocky Linux 9

With HugePages configured, you may want to know how many a particular process uses. These methods work on Ubuntu 24.04, Debian 12, AlmaLinux 9 and Rocky Linux 9.

System totals

grep -i huge /proc/meminfo

Per process: explicit HugePages (hugetlbfs)

awk '/Hugetlb/ {sum += $2} END {print sum " kB"}' /proc/1234/smaps

This adds the Private_Hugetlb and Shared_Hugetlb values for process 1234 (replace with your PID). numastat -p 1234 (package numactl) shows the same per NUMA node in the Huge row.

Per process: transparent huge pages (THP)

awk '/AnonHugePages/ {sum += $2} END {print sum " kB"}' /proc/1234/smaps

Databases such as Oracle, PostgreSQL or Java applications often use explicit HugePages; ordinary processes may use THP automatically. Check the THP mode with cat /sys/kernel/mm/transparent_hugepage/enabled.

Reserve HugePages

echo 'vm.nr_hugepages = 1024' > /etc/sysctl.d/90-hugepages.conf
sysctl --system
grep HugePages_Total /proc/meminfo

1024 pages of 2 MB reserve 2 GB of RAM that normal programs cannot use, so size it for the application that needs it.