Re: memory limitation test kit (tm) :-)

["Dr. Werner Fink" <werner@suse.de>]

> Hi there,
> 
> I've made a 'very preliminary' test patch to test
> whether memory limitation / quotation might work.
> It's untested, untunable and plain wrong, but nevertheless
> I'd like you all to take a look at it and point out things
> that I've forgotten in the limitation code...

Hmmm ... this will lead to increasing swap I/O. This because the
tsk which currently swaps in a needed page maybe lose an other
needed page ... even it not lose it the age of such a page is
decreased ... just like a handicap.

          Werner


> 
> -----------------------------------------------------
> --- linux2188orig/mm/page_alloc.c	Thu Feb 26 13:51:16 1998
> +++ linux-2.1.88/mm/page_alloc.c	Thu Feb 26 13:09:17 1998
> @@ -26,6 +26,7 @@
>  #include <asm/bitops.h>
>  #include <asm/pgtable.h>
>  #include <asm/spinlock.h>
> +#include <asm/smp_lock.h> /* for (un)lock_kernel() */
>  
>  int nr_swap_pages = 0;
>  int nr_free_pages = 0;
> @@ -328,7 +329,20 @@
>  void swap_in(struct task_struct * tsk, struct vm_area_struct * vma,
>  	pte_t * page_table, unsigned long entry, int write_access)
>  {
> -	unsigned long page = __get_free_page(GFP_KERNEL);
> +	int i = 0;
> +	unsigned long page = 0;
> +	static int swap_out_process(struct task_struct *, int);
> +
> +	if (vma->vm_mm->rss > num_physpages / 2 && nr_free_pages < 
> +			free_pages_high) {
> +		lock_kernel();
> +		for (i = vma->vm_mm->rss; i > 0; i--)
> +			if (swap_out_process(tsk, __GFP_IO|__GFP_WAIT))
> +				break;
> +		unlock_kernel();
> +	}
> +
> +	page = __get_free_page(GFP_KERNEL);
>  
>  	if (pte_val(*page_table) != entry) {
>  		free_page(page);
> ------------------------------------------------------------
> 
> Rik.
> +-----------------------------+------------------------------+
> | For Linux mm-patches, go to | "I'm busy managing memory.." |
> | my homepage (via LinuxHQ).  | H.H.vanRiel@fys.ruu.nl       |
> | ...submissions welcome...   | http://www.fys.ruu.nl/~riel/ |
> +-----------------------------+------------------------------+
> 
>