But any other unused space is wasted if there’s uncached data on a more distance level of the storage hierarchy.įirst, I can’t possibly figure out how that “it” I replaced could refer to SuperFetch or any similar technology because Linux doesn’t have anticipatory page-in mechanism. Obviously some space will need to remain reserved for paging, dumping the kernel (if so configured), and for emergency maintenance by the superuser.
If the NFS volume is large enough, the cachefs volume should expand to fill your unused and unreserved space. For example, local disk storage should be used as a cache for network resources such as NFS volumes. But more importantly, the system must make the best use of its resources on all levels of the storage hierarchy. AIX), some portions of physical memory may never be paged to disk. Even on systems with pervasive support for pageable kernelspace (i.e. The fact of the matter is that physical memory is a resource. When the disk cache hit-rate drops, read performance on NTFS becomes unacceptable, nearly as bad as FAT32.
#Memory monitor vista windows#
In fact, I’m sure that any Windows OS that had support for NTFS must have also featured a disk cache, since the basic design consideration for NTFS is that reads should usually be satisfied from the disk cache. There are classic OS textbooks that describe these mechanisms in great detail. This was a bug that some users hit while running the 32-bit Vista installer on systems with 3GB+ of memory. If it’s set to allocate 3GB, you run the risk of starving your userspace applications of virtual memory, causing them to crash. Basically, if you have 4GB of memory installed, and you’re running a 32-bit OS, the kernel can only allocate 1-3GB of this memory no matter how small the memory requirements of userspace might be. This limit must be set no later than boot-time (usually it is set at install-time) and depends on how much physical memory you have installed on your system. The kernel does have a hard limit on virtual address space with comes into play on 32-bit systems (or 64-bit systems running a 32-bit OS). The buffer cache is still used for caching inherently block-sized storage objects such as inodes and other filesystem metadata objects. In Linux 2.6, the disk cache is implemented mostly through the page cache, which uses larger and more well-behaved (with respect to alignment) virtual memory pages as the fundamental unit of storage.
Now, to be fair, Linux 2.4 implemented disk caching through the buffer cache, which uses disk blocks as the fundamental unit of storage. Linux and every other major UNIX-like system back to at least SVR4 and beyond has had a disk cache that consumes any otherwise unused physically-resident virtual memory allocated to the kernel. That’s the funniest thing I’ve read so far today.
#Memory monitor vista update#
RAMMap's refresh feature enables you to update the display and it includes support for saving and loading memory snapshots.įor definitions of the labels RAMMap uses as well as to learn about the physical-memory allocation algorithms used by the Windows memory manager, please see Windows Internals, 5th Edition.I don’t even think Linux had when Windows XP first came out because they were still dealing with the 2.4 kernel. Use RAMMap to gain understanding of the way Windows manages memory, to analyze application memory usage, or to answer specific questions about how RAM is being allocated.
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