Messages in this thread | | | From | KOSAKI Motohiro <> | Subject | Re: [patch 3/3] mm: keep pages from unevictable mappings off the LRU lists | Date | Mon, 23 Mar 2009 11:21:36 +0900 (JST) |
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> Hmm,, > > This patch is another thing unlike previous series patches. > Firstly, It looked good to me. > > I think add_to_page_cache_lru have to become a fast path. > But, how often would ramfs and shmem function be called ? > > I have a concern for this patch to add another burden. > so, we need any numbers for getting pros and cons. > > Any thoughts ?
this is the just reason why current code don't call add_page_to_unevictable_list(). add_page_to_unevictable_list() don't use pagevec. it is needed for avoiding race.
then, if readahead path (i.e. add_to_page_cache_lru()) use add_page_to_unevictable_list(), it can cause zone->lru_lock contention storm.
then, if nobody have good performance result, I don't ack this patch.
> On Mon, Mar 23, 2009 at 5:13 AM, Johannes Weiner <hannes@cmpxchg.org> wrote: > > Check if the mapping is evictable when initially adding page cache > > pages to the LRU lists. ?If that is not the case, add them to the > > unevictable list immediately instead of leaving it up to the reclaim > > code to move them there. > > > > This is useful for ramfs and locked shmem which mark whole mappings as > > unevictable and we know at fault time already that it is useless to > > try reclaiming these pages.
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