[webkit-dev] memory consumption

Darin Adler darin at apple.com
Wed Jul 2 12:57:18 PDT 2008

On Jul 2, 2008, at 7:19 AM, Akos Kiss wrote:

> I'd like to ask you whether the memory consumption of the JS engine  
> is of importance for you or does performance have higher priority?

Memory consumption is quite important.

> we found in the newest version of the RegisterFile that it's memory  
> consumption is quite high by default: ~8megs in a 32bit system and  
> ~16megs in a 64bit system.

The new RegisterFile uses virtual memory mapping to allow the register  
file to expand, without changing its base address.

Tools to tell you how much memory is consumed may not give a correct  
indication of how much memory is actually being consumed; instead they  
might reflect the large amount of virtual space that's mapped but not  
actively used. This space should not cost anything.

This depends a lot on the platform and underlying OS.

On Windows we intend to use VirtualAlloc, but it's not yet  
implemented. So currently on Windows you will see a lot of memory used!

If neither the mmap nor the VirtualAlloc mechanism is efficient on a  
particular platform, we would take patches to refine RegisterFile.h to  
use other techniques suitable for other platforms.

     -- Darin

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