In kreclaimd() there is a nice loop that looks like
for(i = 0; i < MAX_NR_ZONES; i++) {
zone_t *zone = pgdat->node_zones + i;
if (!zone->size)
continue;
while (zone->free_pages < zone->pages_low) {
struct page * page;
page = reclaim_page(zone);
if (!page)
break;
__free_page(page);
}
}
I was playing around with the page age algorithm when i noticed that it
appears that the machine will get into a state where the inner loop _NEVER_
exits the current zone because applications running in that zone are eating
the memory as fast as it is being freed up. I imaging that this could be
causing some pretty serious problems since the other zone's pages will only
get recleaimed during a page alloc. Maybe there should be a max number of
pages that can be reclaimed out of any given zone to force this loop to
break? Something like 5 or 10% of the zone?
Any comments?
BTW: I started playing with the page age system when I noticed that it
wasn't very evenly distributed. All the pages in a tend to fall into one or
two age groups pretty close to PAGE_AGE_START with a significant number of
them often below PAGE_AGE_START.
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This archive was generated by hypermail 2b29 : Tue Aug 07 2001 - 21:00:28 EST