Hi!
> diff -urN linux-2.5.26-rmap/Documentation/vm/overcommit-accounting linux/Documentation/vm/overcommit-accounting
> --- linux-2.5.26-rmap/Documentation/vm/overcommit-accounting Wed Dec 31 16:00:00 1969
> +++ linux/Documentation/vm/overcommit-accounting Wed Jul 17 10:45:47 2002
> @@ -0,0 +1,77 @@
> +The Linux kernel supports four overcommit handling modes
> +
> +0 - Heuristic overcommit handling. Obvious overcommits of
> + address space are refused. Used for a typical system. It
> + ensures a seriously wild allocation fails while allowing
> + overcommit to reduce swap usage. This is the default.
> +
> +1 - No overcommit handling. Appropriate for some scientific
> + applications.
> +
> +2 - (NEW) swapless strict overcommit. The total address space
> + commit for the system is not permitted to exceed 95% of
> + free memory. This mode utilizes the new stricter accounting
> + but does not impose a very strict rule. It is possible that
> + the system could kill a process accessing pages in certain
> + cases. If mode 3 is too strict when no swap is present
> + this is the best you can do.
> +
> +3 - (NEW) strict overcommit. The total address space commit
> + for the system is not permitted to exceed swap + half ram.
> + In almost all situations this means a process will not be
> + killed while accessing pages but only by malloc failures
> + that are reported back by the kernel mmap/brk code.
In what scenario can "strict overcommit" kill?
> +4 - (NEW) paranoid overcommit. The total address space commit
> + for the system is not permitted to exceed swap. The machine
> + will never kill a process accessing pages it has mapped
> + except due to a bug (ie report it!).
...and why is that scenario impossible on "paranoid overcommit"?
Pavel
-- I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care." Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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