This reduces the amount of memory available to the Operating System, thus applications may incur a higher rate of hard page faults. In order to operate, they must carve out some amount of Physical Address Space. Now, as it relates to RAMDrives, such as DIMMDrives or any number of free alternatives. Yes, even SSDs need to be defragmented, and Windows 8 does defragment SSDs. This can be measured by the performance counter named Split I/O, and usually a drive needs to be fragmented once it reaches ~30% of the Total I/O counter. This makes accessing files quicker than they otherwise would be. Windows has descriptors for every file on an NTFS volume, or references to MFT descriptors outside of the MFT. These are good! This means the application was able to read the Standby list and bring the file back into the Active list in memory. Of course, this will often happen when an application starts. This means that your application must go back to disk in order to read the file. If there is enough free memory, the Operating System will keep files in the Standby list as they may be used again, and it is quicker to read from memory than it is to go back to disk, obviously. This is memory that contains files and data that isn't in active use, but was recently used. The Active list will hold both files and data.Īka in part file cache. This is memory in active use by an application. Applications do not necessarily load the entire file into memory. In order to memory-map a file, you must simply read it for example, using the ReadFile or ReadFileEx Win32 APIs. Memory-mapped files are files present in memory, either in the Active or Standby lists. Programs like DIMMDrive leverage kernel-mode drivers, which allows it to directly address Physical Address Space. This is addressable by the Operating System only. This is all of the physical memory in your system, mostly RAM. Applications do not have access to RAM, but rather to Virtual Address Space which is managed by the Operating System. VM/VAS are interchangeable and VM does not mean "page file" or "swap file". This is memory that applications can see/use. This will be a little education on the technical implications of RAMDrives, as well as a bit of background on the Virtual Memory Manager.
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