Review request for 5049299 (original) (raw)

Andrew Haley aph at redhat.com
Sat May 23 08:28:43 UTC 2009

Martin Buchholz wrote:

On Fri, May 22, 2009 at 15:13, Michael McMahon <Michael.McMahon at sun.com>wrote:

Martin,

Thanks. Great comments. Just a few comments of my own on a couple of points. 1. Linux won't benefit from this change as much as solaris, since due to its "memory overcommit" architecture, it doesn't suffer from the problem (so much) in the first place (though memory overcommit causes some problems of its own). Nevertheless, maybe it could simplify the code a bit if we use posixspawn() on Linux as well. So, I will look into that. Any company running server farms (think "Sun" or "Google") would like to "bin-pack" as many processes as possible onto them, and transient doubling of process size is a big problem in such an environment. Think of this as a saving-the-planet-from-global-warning feature.

But those running Linux won't benefit from such a change because on Linux there is no transient doubling of process size: all that happens is that the page table entries in the new process are mapped copy on write. The extra pages count towards the overcommit limit, but that's wholly artifical.

Andrew.

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