Linux Kernel Newbies -- Re: Lists LRU

On Tue, May 13, 2008 at 7:58 AM, Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx> wrote:

Hi Eduardo...

Good questions...

On Tue, May 13, 2008 at 9:02 AM, Eduardo Júnior <ihtraum18@xxxxxxxxx> wrote:
>
> Hi,
>
> I read that the lists LRU (active and inactive) store working set of the
> processes that are running.

not only process owned pages, but kernel allocated ones such as
buffer, socket buffer and so on AFAIK.

> I read that also on the active list is two-thirds of the inactive list.

Hmmm? never measure it...but that's possible...even more I guess...
depending on current real memory pressure..

I have read this information in the mel gorman's PDF, but this is not something fixed and determined.
The system tries to maintain this proportion in the sizes of the lists.
Hence, there should be any policy that would try to be achieved.

That policy should be static (I think), even the lists LRU structures and dynamics, as you have said.

I concluded that this policy is to not increase the number of pages scanned when the policy of replacing pages is applied, not increasing the overhead. In my view, that's the only explanation to maintain this proportion in size between the LRU lists.

> My source has not informed as the size of the inactive list was defined, if
> at compile time or runtime.

not defined AFAIK. it's entirely a dynamic data structure.

> So, I wonder:
>
> - The size of the inactive list is defined that way?

nope, dynamic..

> - The definition of the size of the inactive list has some dependence on
> architecture?

nope...

> - The lists are initialized in the boot?

AFAIK yes

>Only pages of the image and
> structures of pages of the kernel are these lists? What kinds of pages they
> store?

any kind of allocated pages..by allocated i mean the one which is
allocated via kmalloc() and friends and not locked into RAM and must
exist in the entire life of the kernel.

I din't understand well that part

> Any reference to respect would be welcome.

Sorry, none that I have. maybe mel gorman's PDF.

I'm already reading this PDF. ;)