Question: How to Calculate the percentage of memory reserved by Huge Pages?
1. Inspect the memory parameters:
# cat /proc/meminfo MemTotal: 98721456 kB MemFree: 1277612 kB MemAvailable: 12186676 kB Buffers: 20496 kB Cached: 11013124 kB SwapCached: 4820 kB Active: 2303780 kB Inactive: 9716992 kB Active(anon): 716672 kB Inactive(anon): 582092 kB Active(file): 1587108 kB Inactive(file): 9134900 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 33554428 kB SwapFree: 32965424 kB Dirty: 16856 kB Writeback: 0 kB AnonPages: 1004112 kB Mapped: 308188 kB Shmem: 290944 kB Slab: 694100 kB SReclaimable: 602280 kB SUnreclaim: 91820 kB KernelStack: 13792 kB PageTables: 75736 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 40956756 kB Committed_AS: 3011596 kB VmallocTotal: 34359738367 kB VmallocUsed: 256480 kB VmallocChunk: 34359477292 kB HardwareCorrupted: 0 kB AnonHugePages: 0 kB CmaTotal: 0 kB CmaFree: 0 kB HugePages_Total: 40975 HugePages_Free: 35867 HugePages_Rsvd: 13 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 163840 kB DirectMap2M: 14516224 kB DirectMap1G: 87031808 kB
2. Calculate the percentage of memory used by HugePages:
memory% = (HugePages_Total * Hugepagesize) / MemTotal * 100.0
3. Use the values appropriate for your system, taken from the /proc/meminfo report. For example, from the example above:
memory% = (HugePages_Total * Hugepagesize) / MemTotal * 100.0 memory% = (40975 * 2048) / 98721456 * 100.0 memory% = 83916800 / 98721456 * 100.0 memory% = 85.04
The HugePages configuration reserves about 85% of the physical memory on the server.
Note that all values in /proc/meminfo use the same units, so no conversion is necessary.