Review request for 5049299
aph at redhat.com
Sun May 24 09:16:19 UTC 2009
Martin Buchholz wrote:
> I did a little research.
> The overcommitment policy on Linux is configurable
> Of course, almost everyone will use the default "heuristic" policy,
> and in this case the COW memory after fork() is subject to overcommit
> accounting, which *may* cause the fork to fail.
Sure, it *may*, but I don't think it's at all common.
> If a solution using clone(CLONE_VM ...) can be made to work,
> subprocess creation will be a little cheaper and significantly more
Maybe, but I think that needs to be measured before any changes are made.
I'm not opposed to such a change that makes a real improvement, but I'm
not convinced it will. As usual, I'm happy to be proved wrong.
There may be a kernel bug in the case described in the mail above: it
certainly should be possible to fork a 38 GB process on a system with
64 GB RAM. If so, I expect that this will be fixed long before any Java
VM change makes it into production.
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