Memory Fragmentation

[ASOEASTGEOGRAPHY]

Can main memory fragmentation cause significant performance problems?

[Sam Nicholls]

I don't believe there is any benefit to having concurrent virtual pages mapped to concurrent physical pages. The hardware still has to go through the Translation Lookaside Buffer to convert a virtual address to physical.

Depending on the application's memory access patters, you may get a significant performance boost on HP-UX 11.0 by increasing the page size. If the appliation does sparse memory accesses, then increasing the page size will reduce the number of TLB lookups (and thus the possibility of expensive TLB misses).

To increase the page size of an application, use chatr like...

chatr +pd 64K a.out

See the chatr manpage for more info.

-sam