Aaron Konstam wrote:
Well this is an interesting article but it tells one nothing about swap fits into the virtual memory structure for the 2.4 kernel in this case.
No, but it does cover the "overcommit" feature of the Linux VM. Understanding overcommit and the requirements of fork() in a posix environment are critical to deciding how much swap you need.
Generally, the overcommit feature may allow some things to work better, but introduces some serious problems when the assumptions behind overcommit don't apply. Hence, it's off by default. If you're not using overcommit, then you should have considerably more swap than you intend to actually use. Swapping is slow, and many people prefer to have very little because they believe that if they allow memory use to grow that large, the system will be very slow to respond. In some cases they are right. However, if you have insufficient swap, the login processes may not be able to fork, and you may not be able to log in and correct the problem. Larger applications may be unable to fork, and use external helpers, even when there appears to be sufficient memory for the helpers.
I'm of the opinion that it's best to have plenty of swap, as previously discussed.
