How Changing Virtual Memory In Vista Can Improve Your PC

Instructions provided describe how to adjust the system's virtual memory settings. For the maximum benefit, set this value to the maximum available on the Windows operating system. For Windows 2000 and XP, the maximum available is 4096MB (4GB).

How To Change Virtual Memory In Vista

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The drive selected for the virtual memory should have enough free space to store the page file, as defined by the initial and maximum settings. If the amount of free space on the drive is less than the virtual memory settings, the page file size uses all the available drive space. In that case, clear some space on the drive or set the virtual memory to another drive.Windows 10:See the Microsoft Help topic: "How to Increase Virtual Memory in Windows 10: A Quick Guide".

If you use applications that needs more memory, or your system is very slow, or crashes with blue screens (e.g. BSOD PAGE_FAULT_IN_NONPAGED_AREA, etc.) then increase you virtual memory size by following the steps below:

This change occurs because Windows Vista with SP1 reports how much physical memory installed on your computer. All versions of Windows NT-based operating systems before Windows Vista Service SP1 report how much memory available to the operating system. This change in Windows Vista SP1 is a reporting change only.You will see this reporting change in the following locations:

Important This change in reporting does not address all differences in memory reporting. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Computer pagefile is a temporary file area set aside by Windows for use when physical memory (RAM) is exhausted. It is also known as "page file" or "swap file". More on how LUSAS uses PC virtual memory

We would recommend setting the size is set to that "Recommended" in this dialog (which is generally 1.5 times the amount of RAM installed) and locating the page file on a local disk drive with plenty of free space available. Depending on how many local drives are in use on the PC and their capacities, it may be advantageous to locate the PC virtual memory on a different local drive from other Windows temporary files, LUSAS temporary files and on a different local drive from where you store any large models and results files. Note that LUSAS temporary files can become very large and reduce the disk space available for the dynamic growth of the PC virtual memory.

user space virtual memory space is limited to 2G normally, but physical disk page storage could be much larger than 2G. Since there are more disk pages than virtual memory pages, so in theory more than one disk pages could be mapped to one virtual address page. If user request to access some virtual address, how did memory manager know which disk page should be accessed if more than one disk pages are mapped to one virtual address page?

I do not know why there is restrictions like byte[] array must use continuous virtual memory space. I think in theory even if we only allocate 500M virtual space address, we can re-use such virtual space address to continue to map/unmap disk page file to consume as much as we want, even larger than 2G.

byte (or any other) arrays must use contiguous address space, in this case contiguous virtual address space. This is an area that can make fragmentation becomes an issue, and is actually exacerbated by virtualization of memory. Since the various 'redirections' inherent in a such a system system and the performance considerations in making it efficient lead to actual allocation of physical address space mapped to virtual address space in chunks (commonly pages).

So requesting a 10 byte chunk of virtual address space might actually lead to a whole 4K page being reserved and mapped. Since the physical memory within the page must be contiguous this can lead to a whole 4K of virtual address space being 'blocked off'.Multiple small allocations can be placed within one page (and good memory managers will try to achieve this) but none the less address space has in effect been reserved over and above what was strictly required. Consider the allocation of a single byte at the start f a page, then 4K - 2 bytes followed by another single byte. This occupies (efficiently) the whole page.Consider if the middle allocation is no longer necessary, and is thus freed. Until the 'top' and 'tail' values are either freed or moved elsewhere a gap has been created in the virtual address space which can only be filled by something

The only REAL reason we see to adjust the pagefile is if you run into trouble. If you're experiencing issues with pagefile/virtual memory(BSOD), your device doesn't have enough memory, or you're trying to improve the system performance, Windows 10 allows you to increase the size of the virtual memory in at least two ways using the Settings app and Command Prompt.

Although it's possible to disable virtual memory on Windows 10, even when you have a large amount of system memory, it's not recommended to disable this feature. Usually, if you disable paging file, some applications may stop working, some system features may not work efficiently, and you may end up with some weird behaviors.

You can disable the paging file to free up space that would have otherwise been set aside on your SSD by the operating system. But bear in mind this move isn't without risks. Should your system run out of physical memory, the fact that there is no virtual memory available to allocate means that subsequent crashes are quite likely. Really, this mostly makes sense if you have a ton of RAM and aren't worried about the potential for data loss should an application crater in the event your system exceed what is installed.

When working with large files in CorelDRAW, it may be required to increase the amount of memory allocated to the application. Default memory allocation is set to 25%. This can be increased to as high as 50%, though it is not recommended to exceed this level. Increasing this setting beyond 50% will reduce the amount of RAM being used by Windows, decreasing performance of the entire computer. It may also be required to change drives being used as swap disks. Drives with a high capacity of free space are ideally suited for swap disks. It is also recommended that the primary disk be set to a drive which does not contain the Windows partition. This will improve read and write times if specifying a drive with little or no disk activity.

MIMIC runs onWindows Vista Business EditionWindows Server 2008Windows 7Windows Server 2012Windows 8Windows 10Windows Server 2016 StandardWindows Server 2019Windows 11It is highly recommended to install the latest service pack for therespective OS. The following aresome of the most common problems encountered on Windows, and their fixes:Back to TopAccount PrivilegesFor Windows Vista, Server 2008 and Windows 7 and newer, please go tothe section below.Back to TopFirewallsDue to pervasive security attacks against Windows systems connected tothe Internet, it has become common to run a software firewall on recentversions of Windows.MIMIC will coexist with a software firewall, provided that the firewall isconfigured to recognize MIMIC as a program allowed to access the network.MIMIC will, due to its very nature of simulating networked components,open network sockets and communicate with external applications(eg. network management applications, telnet clients, etc).There are certain components of MIMIC that will access the Internet(eg. specific web sites to determine software updates, etc), but onlyif explicitly configured by the user.Back to TopAssigning IP AddressesMIMIC requires at least one operational network interface card (NIC).On Windows Vista or later, as on theUnix platforms, MIMIC dynamically assigns IP addresses when starting eachagent instance.Back to Top5000 / 10000 agent supportDifferent versions of Windows have performancelimitations while running large numbers of IP addresses. The followingare the limits on the different versions of Windows:Windows Vista: 10000 agents;Windows Server 2008: 10000 agents;Windows 7: 10000 agents;Windows Server 2012: 30000 agents;Windows 8: 30000 agents;Windows 10: 30000 agents;Windows 11: 30000 agents;In empirical tests, going beyond those limits introduced non-deterministicinstability and performance problems.Back to Top20000 / 30000 agent supportYou can run 20000 agents only on Windows Server 2003, and 30000 agentsonly on Windows Server 2012, 2019, Windows 8, 10, 11, and then only with64-bit executables,and more on the Unix platforms.Back to TopVirtual MemoryMIMIC is a specially memory-intensive application, and it needs plenty of physical memory (RAM) and virtual memory (swap space) for the more complexdevice simulations. We recommend an absolute minimum 1 GBof RAM and 2 GB of swap space to start. Verify that you have enoughswap space in the System Control Panel.You should as a rule of thumb have twice the swap space as your physicalmemory.Different versions of Windows on Intel systems impose different limitson the amount of virtual memory accessible for the MIMIC Simulator,but currently the absolute limit is below 4 GB due to 32-bit addressinglimitations, which the64-bit architecturedoes not have.On all 32-bit versions of Windows there is a 2 GB limit on per-processvirtual memory. The following steps only apply to legacy 32-bit systems.On Windows Vista and later Microsoft has removed the boot.ini file and provided the BCDEdit command to enable 3 GB addressing as documented in this document.To enable this expanded capability on Windows Vista and later, as an Administratorin a Command Prompt window, type the command:BCDEdit /set IncreaseUserVA 3072And then restart your computer.This will make "a full 3 GB of virtual address space available to applications and reduces the amount available to the system to 1 GB."Back to TopDuplicate IP AddressFor Windows Vista, Server 2008 and Windows 7 and later, please go to the section below.If Windows detects that an IP address on one of its Network InterfaceCards (NICs) conflicts with another system (duplicate IP address), thenit tries to resolve this problem by shutting down the NIC and displaysa message such as:The System has detected an IP address conflict with another system on thenetwork. The local interface has been disabled. More details areavailable in the system event log. Consult your network administrator toresolve the conflict.You must not have duplicate IP addresses on a connected network, neitherwith MIMIC or otherwise.NOTE: you can disable duplicate IP address detection by following theinstructions in the article in the (now defunct)Microsoft Knowledge Base titledHow to Disable the Gratuitous ARP Function.It is appended here:How to Disable the Gratuitous ARP FunctionView products that this article applies to.Article ID:219374Last Review:February 24, 2007Revision:3.2This article was previously published under Q219374SYMPTOMSWhen a Windows NT-based computer starts, a packet is broadcast on thenetwork containing the computer's TCP/IP address to prevent the use ofduplicate addresses on the same network. This is called a gratuitousAddress Resolution Protocol (ARP) packet. Routers and other networkhardware may cache routing information gained from multiple gratuitousARP packets. For both performance and maintenance reasons, it is possibleto disable this feature in Windows NT.RESOLUTIONTo resolve this problem, obtain the latest service pack for WindowsNT 4.0. For additional information, click the following articlenumber to view the article in the Microsoft Knowledge Base: 152734( -US/) How to Obtain the LatestWindows NT 4.0 Service PackSTATUSMicrosoft has confirmed that this is a problem in the Microsoft productsthat are listed at the beginning of this article. This problem was firstcorrected in Windows NT 4.0 Service Pack 5.MORE INFORMATIONTo disable gratuitous ARPs after applying this hotfix:1.Click Start, click Run, type regedt32, and then click OK.2.On the Windows menu, click HKEY_LOCAL_ MACHINE on Local Machine.3.Click the \System\CurrentControlSet\Services\TcpIp\Parameters folder.4.Double-click the ArpRetryCount value, type 0, (for Windows XP, type 1) and then click OK.5.Quit Registry Editor, and then restart the computer.Back to TopMedia Sense on Windows Vista and newerNewer versions of Windows (Windows Vista onwards) have a TCP/IP feature whereby it can sense if aNIC is actually connected to the network. By default, a NIC is disabledif it is not found to be on the network, which prevents agents fromstarting in MIMIC. There is a way to disable this behaviourso that you can work on standalone Windows machines. Attachedis an excerpt of theMicrosoft KBarticle on this topic... Please remember to make a copy of your registrybefore making any changes just to be on the safe side.NOTE Windows Vista and newer have no way to disable thisfeature. You can only run MIMIC on Windows Vista and newer withthe system connected to a network.How to disable the Media Sensing feature for TCP/IP in WindowsSUMMARYOn a Windows-based computer that uses TCP/IP, you can use the MediaSensing feature to detect whether the network media are in a linkstate. Ethernet network adapters and hubs typically have a "link" lightthat indicates the connection status. This status is the same conditionthat Windows interprets as a link state. Whenever Windows detects a"down" state, it removes the bound protocols from that adapter untilit is detected as "up" again. Sometimes, you may not want the networkadapter to detect this state. You can set this configuration by modifyingthe registry.Let me fix it myselfImportant This section, method, or task contains steps that tell you howto modify the registry. However, serious problems might occur if youmodify the registry incorrectly. Therefore, make sure that you followthese steps carefully. For added protection, back up the registry beforeyou modify it. Then, you can restore the registry if a problem occurs. Formore information about how to back up and restore the registry, click thefollowing article number to view the article in the Microsoft KnowledgeBase: 322756 How to back up and restore the registry in WindowsTo prevent the network adapter from detecting a link state, follow these steps.Note The NetBEUI protocol and the IPX protocol do not support Media Sensing. Start Registry Editor. Locate the following registry subkey: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters Add the following registry entry to the Parameters subkey: Name: DisableDHCPMediaSense Data type: REG_DWORD (Boolean) Value: 1 Note This entry controls the behavior of Media Sensing. By default, Media Sensing events trigger a DHCP client to take an action. For example, when a connect event occurs, the client tries to obtain a lease. When a disconnect event occurs, the client may invalidate the interface and routes. If you set this value data to 1, DHCP clients and non-DHCP clients ignore Media Sensing events. Restart the computer.Back to TopIPv6 SupportIPv6 is supported only on Windows Vista and newer. This is an OS platformlimitation.IPv6 is installed as detailedhere.IPv6 addresses use an additional Scope ID as detailed on theMicrosoft web-site.If the IPv6 module gets corrupted, you can fix this with thiscommand from the COMMAND prompt:netsh interface ipv6 reset 2ff7e9595c