HugePages Calculator
Calculate the number of HugePages needed to back a given amount of application memory.
About HugePages Calculator
HugePages reduce Translation Lookaside Buffer (TLB) misses for memory-intensive applications like databases by using much larger page sizes (2MB or 1GB) instead of the standard 4KB page. The number of huge pages required is the required memory divided by the huge page size, rounded up, since HugePages must be allocated in whole units. Any excess from rounding is memory reserved but unused by the target application.
Formula
Huge pages required
nr_hugepages = ceil(required_memory_MB / hugepage_size_MB)
- M
- required memory in MB
- H
- huge page size in MB
Worked example
With the default values below, HugePages Calculator returns nr_hugepages of 4,096. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Required Memoryminimum 0 MB
- 8,192 MB
- HugePage Sizeone of 2 MB (standard), 1024 MB (1GB gigantic pages)
- 2 MB (standard)
Results
- nr_hugepages
- 4,096
- Allocated Memory
- 8,192.00 MB
- Rounding Overhead
- 0.00 MB
- sysctl Command
- sysctl -w vm.nr_hugepages=4096
Step by step
- 1Values used
- 2Huge pages required
- 3nr_hugepages= 4,096
- 4Allocated Memory= 8,192.00 MB
- 5Rounding Overhead= 0.00 MB
- 6sysctl Command= sysctl -w vm.nr_hugepages=4096
Assumptions and limits
- The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why use HugePages instead of the default 4KB pages?
Larger pages mean fewer page table entries are needed to map the same amount of memory, which reduces TLB misses and page table walk overhead — a meaningful performance gain for applications with large, actively-used memory regions like database shared buffers.
What is the difference between 2MB and 1GB huge pages?
2MB pages are the standard HugeTLB size supported on virtually all x86_64 systems and can be allocated dynamically at runtime. 1GB 'gigantic' pages need CPU and kernel support, are typically reserved at boot time via a kernel parameter, and are used for very large, static memory regions.
Once allocated, can HugePages memory be used by other applications?
No — memory reserved for HugePages is removed from the normal page allocator and can only be used by applications explicitly requesting huge pages, so over-allocating wastes RAM that regular processes could have used.