Messages in this thread | | | Date | Tue, 21 Mar 2000 07:54:47 -0500 (EST) | From | George <> | Subject | Re: Some questions about linux kernel. |
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On Mon, 20 Mar 2000, David Whysong wrote:
>On Mon, 20 Mar 2000, Richard B. Johnson wrote: > >>The place where all of the system information is known is in "user >>space". The kernel readily "knows" stuff about the current process, but >>retrieving information about other tasks in a page-fault handler would >>result in an extremely poor performing machine. A user-space daemon can >>acquire information about all the tasks, can detect runaway tasks, can >>safeguard special tasks like Web Servers that haven't gone crazy, and >>can watch for performance hurting rogue programs. >> >>Such a program, if properly designed, is the solution to such >>out-of-memory conditions. > >No! Or perhaps it depends on what you want this user-space daemon to do.
Probably mlockall() and then wake up periodically checking for low-memory. If it gets below a certain threshold, use some magic voodoo heuristics (loaded from a configuration file likely) and kill something.
>Once you reach the OOM condition, this program can not reliably run. And I >doubt that a user-space daemon could prevent OOM from happening on a time >sharing system, since a malicious (or buggy) program could try to use all >memory during a single timeslice.
While everything else is paging to disk, I would assume the above program would get lots of time since it's the only thing left that can run. I haven't tried it, but it would make sense.
-George Greer
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