[Webkit-unassigned] [Bug 61137] Don't allocate 1Gb at startup on x86_64 && !Linux

Fri Jun 17 13:02:43 PDT 2011

https://bugs.webkit.org/show_bug.cgi?id=61137

Gavin Barraclough <barraclough at apple.com> changed:

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                 CC|                            |barraclough at apple.com

--- Comment #1 from Gavin Barraclough <barraclough at apple.com>  2011-06-17 13:02:43 PST ---
> From my understanding of the comments in bug 53352 (i might be wrong), the 1Gb allocation on X86_64 is done to allow huge regressions tests to pass fine on linux/x86_64.

No, this does not relate specifically to huge regression tests, or to Linux.  We allocate all VM space for JIT code up front, such that we can ensure locality in the VM space.

> While i won't debate on that particular point, could it be made to be linux-only, so that we don't have to patch that code to remove that insane greedy allocation ?

1GB is less than 1% of 1% of the process's available VM, which can hardly be described as insanely greedy.  :-)

The key here is that the allocation should be of VM space only.  OS X & Windows support lazy commit of memory, so this isn't a problem.  On Linux, the solution to get the right behaviour was landed in this bug: https://bugs.webkit.org/show_bug.cgi?id=42756 , passing the MAP_NORESERVE flag to mmap.  If OpenBSD supports this flag, this is likely the right fix for you, too.  If not, you need to find a mechanism to allocate VM without committing the physical pages up front.

If you wish to submit changes back to trunk, please attach a patch, instructions here:
http://www.webkit.org/coding/contributing.html

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