The page file is there to provide space for whatever portion of virtual memory has been modified since it was initially allocated. In a conversation I had with Mark Russinovich this is stated quite eloquently:. The commit limit is the sum of most of physical memory and all paging files. In the background the system will write these pages out to the paging file if a paging file exists and there is space in the paging file. This is an optimization only. Modified information cannot have backing store to the original file or.
Different types of things are paged to different files. You can't page "private writable committed" memory to exe or. With this understanding we realize:. You see now, in a situation as such, when memory needs to be reclaimed, you'll be paging and unloading the other things in order to take up the necessary slack you've lost by having a page file smaller then the memory in use, the private writable pages can no longer be backed if you've taken away it's page file area.
This is very important for any given workload and ANY amount of RAM, since the OS would like to mark memory available when it's not been called for a long time. You have impeded this strategy if you have a page file lower then the amount of ram in use.
The hits? More paging or backing of executable code, cache data maps and the like. This even though they were referenced far more recently than for arguments sake, the bottom most pages of a thread's stack. These bottom most pages are what we want paged, not.
You thwart this good strategy when there is a smaller amount of page file then there is the amount of memory in use. And so we see, if memory is in use, it has either come from the hard drive or it will go to the hard drive Now, that's out of the way, let's go further:. When the operating system needs to claim memory, because all memory is currently in use, and you are launching new apps, or loading more info into existing work , the OS obviously has to get the necessary ram from somewhere.
Something in memory will must be unloaded to suit your new work. No one knows what will be unloaded until the time comes as XP will unload the feature that is least likely to come into use again. Memory reclamation in XP even goes further than this to make the process as seamless as possible, using more algorithms than most can appreciate. For instance; there is a "first in first out" FIFO policy for pages faults, there is "least recently used" policy, LRU , and a combination of those with others to determine just what will not be noticed when it's released.
There is also a "standby list". When information hasn't been used in a while but nothing is claiming the memory as yet, it becomes available, both written on disc possibly the page file and still in memory. Oh, did I forget to say? If this information is called before the memory is claimed by a new process it will be brought in without needing anything from the hard drive! Why so much trouble with today's amount of ram? The rest of a program can should be kept out on disk.
This will obviously make available more physical memory to be in use for other more immediate and important needs. You don't keep memory waiting around if it's not likely to be used; you try to have your memory invested in good purpose and function. Here, we take Windows XP for example. After that, you can see the Virtual Memory dialog box. As a matter of fact, you had better set a fixed value for the virtual memory to avoid disk fragmentation.
And the specific values depend on your physical memory size. And it is 1. If your memory size is over 2GB, you need no virtual memory. But, in some special situations, you also need the virtual memory. For instance, your system is low on memory when playing large 3D games and making large pictures, you can consider setting virtual memory.
Setting method as follows:. Let us suppose that you have M memory and you want to set D drive as the virtual memory. At this time, you should remove the default virtual memory C drive at first, and leave the C drive selected. Now, the system will be restarted to make this change take effect.
After that, restart the computer. After restarting, all work has been done. The Win In fact, the Win If the system volume C doesn't have enough free space, you can store it on another partition.
However, how to complete this task? Firstly, you should open the System. Then, in the [Enh] section, change the location of Win At this time, if you want to store the Win By default, the system partition contains paging file. Click the Advanced tab. Click the Settings button under the Performance heading. Click the Change button. Clear the check from the Automatically manage paging file size for all drives box Windows 7 and Windows Vista only.
Click the C: hard drive on the list. Click the No Paging File radio button. Click the Set button. Click the D: hard drive on the list select a different drive letter if needed. Click the Custom Size radio button. Enter the same value in the Initial Size and Maximum Size fields. Previously, he has worked as Documentation Specialist in the software industry, a Technical Support Specialist in educational industry, and a Technical Journalist in the computer publishing industry.
To access this dialog box, open the Control Panel and select the Performance and Maintenance category. Select the Advanced tab, and then click the Settings button in the Performance panel. Figure B The Advanced tab gives you access to some heavy-duty performance tuning options. Figure C The Effects dialog box provides access to some of the most common visual effects.
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