Re: [PATCH] vmscan: evict use-once pages first (v2)

Rik van Riel
2009-04-29T16:18:53Z

KOSAKI Motohiro wrote:
> Hi
>
> Looks good than previous version. but I have one question.
>
>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index eac9577..4471dcb 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -1489,6 +1489,18 @@ static void shrink_zone(int priority, struct zone *zone,
>> nr[l] = scan;
>> }
>>
>> + /*
>> + * When the system is doing streaming IO, memory pressure here
>> + * ensures that active file pages get deactivated, until more
>> + * than half of the file pages are on the inactive list.
>> + *
>> + * Once we get to that situation, protect the system's working
>> + * set from being evicted by disabling active file page aging.
>> + * The logic in get_scan_ratio protects anonymous pages.
>> + */
>> + if (nr[LRU_INACTIVE_FILE] > nr[LRU_ACTIVE_FILE])
>> + nr[LRU_ACTIVE_FILE] = 0;
>> +
>> while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
>> nr[LRU_INACTIVE_FILE]) {
>> for_each_evictable_lru(l) {
>>
>
> we handle active_anon vs inactive_anon ratio by shrink_list().
> Why do you insert this logic insert shrink_zone() ?
>
Good question. I guess that at lower priority levels, we get to scan
a lot more pages and we could go from having too many inactive
file pages to not having enough in one invocation of shrink_zone().

That makes shrink_list() the better place to implement this, even if
it means doing this comparison more often.

I'll send a new patch this afternoon.