Re: real verses Virtual memory
Re: real verses Virtual memory
- Subject: Re: real verses Virtual memory
- From: Shawn Erickson <email@hidden>
- Date: Sat, 10 Oct 2009 09:08:42 -0700
On Sat, Oct 10, 2009 at 8:34 AM, jon <email@hidden> wrote:
is there a way to force it to use real memory rather than virtual?
This is, as stated, nonsensical. Your process works in its own independent
virtual memory space that is mapped to physical RAM as needed by the virtual
memory system. That is how it is for processes. If physical memory becomes
heavily utilized (what the OS always attempts to do, unused physical RAM is
wasted RAM) then you could incur swapping if no non-dirty pages exist but it
isn't clear that is what you are seeing based on the information you posted
and the terminology you have been using.
exactly, I look at Activity monitor, "disk Activity" and i can see a
> spike of disk data read/writes every 20 seconds.
Use something like fs_usage or Instruments to understand what files, etc.
you process is using to understand what the IO is possibly related to. If
you are using WebKit, etc. I bet the disk IO you are seeing is related to
the the caching WebKit, NSURLRequest, etc. can do under ~/Library/Caches.
You can turn off aspects of this if you don't want any on disk caching of
fetched pages, etc. to take place.
If you have code doing IO to files of your own and it is highly unlikely you
aren't going to be access those files again for a "long" while then you
could also look at marking your access to those files as not needing file
caching.
It is very hard to assist you with the limited information about how your
process works, what it does, what API it uses to do things, etc. ...and
exactly what problem you perceive to exist.
Anyway you seem to be confused on how memory is managed in an application
given some of your statements. You may want to find some online resources on
modern virtual memory systems and theory.
-Shawn
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