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USN O6 ![]() Admin Group ![]() Forum Manager Joined: Sep-10-2010 Location: Sarasota, FL Status: Offline Points: 12121 |
![]() Posted: Sep-11-2015 at 6:24pm |
Hi All,
The following excerpt from the iFly 747-400 Tutorial Addendum is of interest to all iFly users and is quoted for info: Virtual Address
Space (VAS)
The Team is seeing an
increasing number of posts at flight sim internet sites and support forums,
including our own , on the subject of OOMs.
The majority of these errors occur in FSX and P3D, but FS9 can also be
involved. So what is an OOM and
how does it happen? First, we need to
have a brief look at Windows memory management.
What follows is from https://msdn.microsoft.com/en-us/library/windows/desktop/aa366779(v=vs.85).aspx There are more details there if you wish to immerse
yourself in details. Windows
Memory Management Each 32-bit process
(FS9, FSX or P3D) on 64-bit Microsoft Windows has its own virtual address space
that enables addressing up to 4 gigabytes of memory. All threads of a process can access its
virtual address space. However, threads cannot access memory that belongs to
another process, which protects a process from being corrupted by another
process. A virtual address does
not represent the actual physical location of an object in memory; instead, the
system maintains a page table
for each process, which is an internal data structure used to translate virtual
addresses into their corresponding physical addresses. Each time a thread
references an address, the system translates the virtual address to a physical
address. We recommend using
Windows 7 64-bit as it provides the full 4GB block of VAS to FSX and P3D. 32-bit Windows provides only a maximum of
2GB of VAS. 32-bit Windows VAS can be
increased to 3GB by using “the 3GB switch”.
See this post for more information:
http://ifly.flight1.net/forums/forum_posts.asp?TID=838&title=accessing-more-memory Nonetheless, the result
of the tweak is 1GB less VAS than with 64-bit Windows. Therefore, OOMs and OS errors will be more
likely. Another great source of
information on this topic is Mark Russinovich’s blog: Implications for FS Everything running as a
part of Flight Simulator consumes part of the 4GB allocated to the
process. So all of that complex scenery,
AI aircraft, clouds, high definition textures, etc., etc. along with complex
aircraft models and the manner in which Flight Simulator and Windows handle
memory can combine to exceed 4GB. That’s
when you see the infamous “Windows has run out of memory and will shut down”
error message. So what’s to do? There are many discussions around the
internet on this topic. One of the more
relevant may be seen at: https://kostasfsworld.wordpress.com/fsx-oom-and-addon-vas-usage/ For P3D, http://www.robainscough.com/Prepar3D_Settings_2.html
provides different settings to test. P3D
users should be aware that the simulation seems to be more sensitive to factors
which cause OOMs. |
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Best,
Jim ![]() ![]() |
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