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Advanced memory management


When installing MIL, the default setup asks the operating system to reserve a portion of RAM from the non-paged memory pool for MIL. By default, this reserved portion of non-paged memory is a single contiguous block that MIL typically uses for grab buffers. The default is usually sufficient and no further action is required on your part. On occasion, it might be necessary to alter how MIL manages this memory. This can occur when you need large buffers and/or a large number of buffers for your application, as well as when you are changing the amount of RAM or the number of PCI devices, such as boards, in your computer.

To make adjustments to MIL's non-paged memory setup, especially the non-paged memory size reserved for MIL, use the MILConfig utility under the Non-paged memory item.

MIL non-paged memory management driver

The MIL non-paged memory management driver uses the operating system's mechanism to reserve the total amount of non-paged memory required for MIL. The mechanism allocates non-paged memory into non-adjacent chunks of contiguous memory. The chunk size depends upon the total RAM installed in your computer, but the size is only relevant if the total non-paged memory requested for MIL is greater than the size of a single chunk. If you request 1 Gbyte of non-paged memory and, based on the amount of RAM in your computer, the chunk size is 256 Mbytes, you will have 4 non-adjacent 256-Mbyte chunks of contiguous memory. In this example, if you allocate two 100 Mbyte grab buffers, they could both exist in a single chunk, but if you allocate two 150 Mbyte grab buffers, they would each occupy a separate chunk, since a single buffer cannot occupy two separate chunks. MIL will not allow you to allocate a buffer larger than the chunk size, by default. To allow very large buffers, you must enable large non-paged MIL buffers using the MILConfig utility.

Note that you might have installed MIL without installing the MIL non-paged memory management driver; this can happen if no boards were selected during MIL installation. If this is the case, there will be no MILConfig utility option to adjust non-paged memory, since there is no driver able to reserve non-paged memory for MIL; consequently, there will be no non-paged memory available for your application. To install the MIL non-paged memory manager driver, you must uninstall and re-install MIL.

Large non-paged MIL buffers

If your application needs individual buffers that are larger than the chunk size, such as for line-scan cameras, you can explicitly allow the MIL non-paged memory management driver to re-allocate memory such that chunk sizes are ignored when allocating buffers. However, if afterwards, you change either the PCI devices in your computer, or the total amount of RAM, the original re-allocation of memory that allowed large non-paged MIL buffers can lead to the problem of memory conflicts and/or an unusable block of memory.

To resolve these problems, you should use a tool in the MILConfig utility that respects both the amount of non-paged memory you reserved for MIL and the new hardware setup. This two button tool is found in the Error Detection sub-item under the Non-paged memory item. Any user can click on the Check Errors button to assess if a hardware change created conflicts or waste, but only an administrator can click on the Repair Errors button to repair the issue. This tool can also be setup to run automatically immediately after logging in. To do so, select the Check errors at each reboot and each time the MILConfig utility starts option and/or the Fix problems when found option. If an error is found while the tool is running, an error message will appear prompting you for further action to repair the issue. If the Fix problems when found option was selected and you logged in as an administrator, the problem will be fixed and a message box will appear prompting a reboot.

You must allow the tool to reboot twice for the fix to take effect.

Note that if a conflict occurs that crashes your computer and prevents a normal boot, press and hold F8 while your computer is booting to enter safe mode. Once in safe mode, open the MILConfig utility and click on the Check Errors button followed by the Repair Errors button. When Windows is running in safe mode, the MILConfig utility's On-Demand mode is enabled by default, and there is no non-paged memory reserved.

On-Demand Mode

If your MIL application sporadically needs more non-paged memory than what was reserved, or the maximum usage is unknown and you want to minimize non-paged reservation, increasing the amount of non-paged memory reserved for MIL might be counterproductive. To accommodate this type of application, enable On-demand mode using the MILConfig utility; the option can be found through the Non-paged memory item. This mode allows MIL to use RAM outside of the non-paged memory reserved for MIL. This mode should be used with caution because the memory outside of the non-paged memory reserved for MIL is taken from the operating system's non-paged memory pool. If the pool is ever exhausted, this might lead to a system crash because of a failed memory allocation by another application or driver.