Messages in this thread | | | Date | Tue, 9 Jun 1998 20:43:35 -0400 (EDT) | From | "Benjamin C.R. LaHaise" <> | Subject | Re: Proposal to fix PGD/PMD lazy deallocation |
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On Sat, 6 Jun 1998, Perry Harrington wrote:
> I exchanged a couple of emails with Alan today, he enlightened me > to a few things. I have an idea to fix the lazy deallocation of > page tables. > > The idea involves 2 changes: > > First, we'd add a pointer to the task_struct and allocate a page > of RAM upon task creation. The page of RAM would be a table > which retained usage counts for PGD's, making them a fast cinch > to clean up on the x86 architecture.
Noooooo!!!!! I don't feel like having an extra 240KB of RAM wasted on my system when it can be easily reclaimed from elsewhere (this works on architechures where sizeof(pgd/pmd) >= PAGE_SIZE -- this is the case for all architechures, isn't it?): each pgd/pmd has a corresponding (struct page), which has an 'atomic_t count'. Now, how about making use of count in the same fashion as with user level pages? I'm thinking ahead here: it would be quite helpful for any future where page tables are swappable...
-ben
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