Pinned memory
GPFS uses pinned memory (also called page pool memory) for storing file data and metadata in support of I/O operations.
With some access patterns, increasing the amount of page pool memory can increase I/O
performance. Increased page pool memory can be useful in the following cases:
- There are frequent writes that can be overlapped with application execution.
- There is frequent reuse of file data that can fit in the page pool.
- The I/O pattern contains various sequential reads large enough that the prefetching of data improves performance.
Pinned memory regions cannot be swapped out to disk, which means that GPFS will always consume at least the value of the pagepool attribute in system memory. So consider the memory requirements of GPFS and other applications running on the node when determining a value for the pagepool attribute.