On 9/14/06, Vin <pane.vinayak@xxxxxxxxx> wrote:
Hi, > > For eg. if the page size is 4kb and the file size is 13kb then it will > consume 4 pages with the last page using only 1 kb of its 4kb. > > So can we have some mechanism to utilize the wasted memory.. > > Can we use dynamic size for the last page so that the memory is not wasted? Page size is architecture dependent. 1. We cant have page sizes something other than what architecture offers.
True
2.AFAIK, architectures doesn't support variable PAGE_SIZE once the system has started . I mean to say, if we chose 4kb then we are avail with 4k size only, not 4MB.
Multiple page sizes CAN and ARE supported after system startup also. On the x86 line of processors, with PSE, we can have 4K, 4M pages at the same time. AFAIK the kernel code segment is stored in two 4MB pages. If you are using PAE, you can have pages of size 2 MB.
3. Does the MMU recognises such dynamic sizes ?
It does. If you look at the page table layout on x86, you will understand how this is supported, better. However there exist separate TLB caches for both 4K & 4M pages.
./v
Bhanu.
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