CODEWITHSUNDEEP
c++linuxpagingswapfile
dan
dan

Reputation: 5417

How to prevent paging for one program / process?

I have a program that requires much memory, like 2/3 of all the physical ram. After some runtime my operating system begins to swap the program to hdd. But I need the program to respond very fast all the time, so I need to prevent paging for that process.

How can you prevent the OS to swap one process?

Thanks for any help!

Upvotes: 17

Views: 3935

Answers (3)

caf
caf

Reputation: 239371

At the start of the program, call:

mlockall(MCL_CURRENT | MCL_FUTURE);

(If you do not have the source to the program, you'll have to debauch the process with ptrace to do this).

Be aware that this will increase the chances of memory allocations made by the process failing.

Upvotes: 8

sleske
sleske

Reputation: 83645

Well, there's mlock for locking memory (telling the kernel it may not be swapped out), but that's meant for relatively small amounts of memory, and would require modification of the program.

The other option might be to adjust Linux's "swappiness", i.e. its tendency to swap out pages. See here for an interesting discussion. That is not possible per process, however.

I'm not aware of any per-process solution for your problem.

Upvotes: 6

dicroce
dicroce

Reputation: 46830

Use mmap() instead of malloc, and use the "MAP_LOCKED" flag. (works on linux > 2.5.37)

Upvotes: 4

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