Re: [PATCH][mm][Fix] swsusp: fix counting of highmem pages

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > > +static inline unsigned int get_kmalloc_size(void)
> > > +{
> > > +#define CACHE(x) \
> > > +	if (sizeof(struct highmem_page) <= x) \
> > > +		return x;
> > > +#include <linux/kmalloc_sizes.h>
> > > +#undef CACHE
> > > +	return sizeof(struct highmem_page);
> > > +}
> > > +
> > 
> > Can we get rid of this uglyness...
> 
> Sure, we can.

Good.

> > > @@ -437,8 +446,14 @@
> > >  
> > >  static int enough_free_mem(unsigned int nr_pages)
> > >  {
> > > -	pr_debug("swsusp: available memory: %u pages\n", nr_free_pages());
> > > -	return nr_free_pages() > (nr_pages + PAGES_FOR_IO +
> > > +	struct zone *zone;
> > > +	unsigned int n = 0;
> > > +
> > > +	for_each_zone (zone)
> > > +		if (!is_highmem(zone))
> > > +			n += zone->free_pages;
> > > +	pr_debug("swsusp: available memory: %u pages\n", n);
> > > +	return n > (nr_pages + PAGES_FOR_IO +
> > >  		(nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE);
> > >  }
> > >  
> > 
> > And just use 2% approximation here, too?
> 
> Well, I don't think so.  It's checking free memory _after_ the highmem
> pages have been "saved" (ie we are ready to create the image and just
> check if there are enough non-highmem pages to do this).  Here we _know_
> exactly how many pages are needed for the image, so we don't need to use
> any "safety margins".

Ah, okay, I see. As long as the include hack is gone, its okay with me.

> > > Index: linux-2.6.15-rc3-mm1/kernel/power/swsusp.c
> > > ===================================================================
> > > --- linux-2.6.15-rc3-mm1.orig/kernel/power/swsusp.c	2005-12-03 00:14:49.000000000 +0100
> > > +++ linux-2.6.15-rc3-mm1/kernel/power/swsusp.c	2005-12-03 21:25:07.000000000 +0100
> > > @@ -635,7 +635,8 @@
> > >  	printk("Shrinking memory...  ");
> > >  	do {
> > >  #ifdef FAST_FREE
> > > -		tmp = count_data_pages() + count_highmem_pages();
> > > +		tmp = 2 * count_highmem_pages();
> > > +		tmp += tmp / 50 + count_data_pages();
> > >  		tmp += (tmp + PBES_PER_PAGE - 1) / PBES_PER_PAGE +
> > >  			PAGES_FOR_IO;
> > >  		for_each_zone (zone)
> > 
> > This part is okay. Just make enough_free_mem use similar code. (If
> > possible, share the code, it is really computing the same thing).
> 
> enough_free_mem() must not take highmem into account, so it has
> to use different code.  IOW, the current implementation is buggy,
> so I'm trying to change it.

Ok, sorry, I did not notice that.
								Pavel
-- 
Thanks, Sharp!