Re: 64 bit OS VS. 32 bit OS
Právě proto. Ono to totiž není nesmyslně, a už vůbec to není kvůli maximalizaci volný paměti. Paměť je totiž naopak "zabraná" co nejvíc kvůli službě Superfetch.Původně odeslal Petrik
Každopádně:
What's more important is that the page file is not the virtual memory; it's where part of the virtual memory is stored. Virtual memory is the term used for a memory system where a process can allocate more memory than the amount of RAM physically present in the system. Virtual memory is what all applications work with (regardless if there is a page file or not): a virtual address space part of which is mapped onto the physical memory, and the rest is stored in the page file when it's not needed.
If there's no page file, then the memory manager is forced to map the whole virtual address space of the process onto the physical memory somehow, which is a pretty tricky thing to do since win32 applications use a 4GB virtual address space, which in most cases is more than the amount of physical memory available (and don't forget that we're talking about every single process currently running on the system, each with it's own 4GB virtual address space). That's when the amount that don't fit in in the physical memory would normally be allocated from the page file, if there is one.
What the Task Manager reports as "VM Size" is actually called Virtual Private Bytes: the amount of non-shareable virtual memory used by the given process alltogether, part of which is currently in physical memory (shown in the Memory Use column) and the rest is paged out (the difference of the VM Size and the Memory Use columns). So the VM Size figure seen here can be more than the size allowed for the page file, since a part (usually almost all of it) of the amount shown here is in the physical memory. Theoretically it could go as high as the sum of the physical memory and the maximum size of the page file (which is the Commit Charge Limit value shown on the Performance tab).
Ještě jsem někde měl uloženej odkaz s nějakým krátkým článkem na tohle téma, zkusím ho najít.
Myth - "Disabling the Paging File improves performance."
Reality - "You gain no performance improvement by turning off the Paging File. When certain applications start, they allocate a huge amount of memory (hundreds of megabytes typically set aside in virtual memory) even though they might not use it. If no paging file (pagefile.sys) is present, a memory-hogging application can quickly use a large chunk of RAM. Even worse, just a few such programs can bring a machine loaded with memory to a halt. Some applications (e.g., Adobe Photoshop) will display warnings on startup if no paging file is present."
"In modern operating systems, including Windows, application programs and many system processes always reference memory using virtual memory addresses which are automatically translated to real (RAM) addresses by the hardware. Only core parts of the operating system kernel bypass this address translation and use real memory addresses directly. All processes (e.g. application executables) running under 32 bit Windows gets virtual memory addresses (a Virtual Address Space) going from 0 to 4,294,967,295 (2*32-1 = 4 GB), no matter how much RAM is actually installed on the computer. In the default Windows OS configuration, 2 GB of this virtual address space are designated for each process' private use and the other 2 GB are shared between all processes and the operating system. RAM is a limited resource, whereas virtual memory is, for most practical purposes, unlimited. There can be a large number of processes each with its own 2 GB of private virtual address space. When the memory in use by all the existing processes exceeds the amount of RAM available, the operating system will move pages (4 KB pieces) of one or more virtual address spaces to the computer's hard disk, thus freeing that RAM frame for other uses. In Windows systems, these "paged out" pages are stored in one or more files called pagefile.sys in the root of a partition. Virtual Memory is always in use, even when the memory required by all running processes does not exceed the amount of RAM installed on the system."
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