Rohan Hawthorne wrote:
>
> Sometimes I just sit on my couch and watch my computer's little light blink.
>
> Why is it blinking ? I'm not sitting on the computer doing anything. It
> shouldn't be
> accessing the harddrive - which is what I've been lead to believe the
> blinking
> represents.
>
> Strange. Maybe it's talking to me like R2-D2.
>
> Rohan.
Unfortunately the buffer cache in Windows XP isn't ideal, based on some
things I've read. For some reason it does disk accesses when it
shouldn't have to. The program image pages should be already cached in
RAM after one use, if they haven't been purged for reuse.
It's a forgiveable problem, because a unified buffer cache is difficult
to implement, and not even unix-like systems always get it right.
Drivers do things they shouldn't at times, things run amuck.
Windows XP essentially starts some services periodically. If you watch
the task list you can see all of the system services that run.
Oh, and a page is a chunk of memory on an Intel x86/Pentium-based
processor that is typically 4096 bytes. It's the smallest unit that is
allocatable by the processor's memory management unit or MMU. Each page
has access permissions. So when a program does something it shouldn't
to its virtual memory, such as writing to a read-only page, or writing
to a page that hasn't been allocated in the page table for that process,
you end up with an "access violation" and the program gets an exception
and usually is forcefully closed by Windows.
Somewhere in that mixture is address translation. Each general program
sees a virtual address space. So programs have a consistent virtual
address space (usually), but a different physical memory address space.
This is an article about some of Microsoft's leaked sources and the
somewhat questionable quality of them:
http://www.kuro5hin.org/story/2004/2/15/71552/7795
George
blinking computer. 
Linear Mode
