Messages in this thread | | | Date | Wed, 1 Apr 2009 14:08:28 +0900 | From | Daisuke Nishimura <> | Subject | Re: [PATCH] vmscan: memcg needs may_swap (Re: [patch] vmscan: rename sc.may_swap to may_unmap) |
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On Wed, 1 Apr 2009 06:09:51 +0200, Johannes Weiner <hannes@cmpxchg.org> wrote: > On Tue, Mar 31, 2009 at 10:48:32AM +0900, KOSAKI Motohiro wrote: > > > > Sorry for too late response. > > > > I don't know memcg well. > > > > > > > > The memcg managed to use may_swap well with global page reclaim until now. > > > > I think that was because may_swap can represent both meaning. > > > > Do we need each variables really ? > > > > > > > > How about using union variable ? > > > > > > or Just removing one of them ? > > > > I hope all may_unmap user convert to using may_swap. > > may_swap is more efficient and cleaner meaning. > > How about making may_swap mean the following: > > @@ -642,6 +639,8 @@ static unsigned long shrink_page_list(st > * Try to allocate it some swap space here. > */ > if (PageAnon(page) && !PageSwapCache(page)) { > + if (!sc->map_swap) > + goto keep_locked; > if (!(sc->gfp_mask & __GFP_IO)) > goto keep_locked; > if (!add_to_swap(page)) > but it doesn't work for shmem/tmpfs, does it? So, I did in my first patch like:
@@ -616,6 +619,11 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (!sc->may_unmap && page_mapped(page)) goto keep_locked; + if (!sc->may_swap && PageSwapBacked(page) + /* SwapCache uses 'swap' already */ + && !PageSwapCache(page)) + goto keep_locked; + /* Double the slab pressure for mapped and swapcache pages */ if (page_mapped(page) || PageSwapCache(page)) sc->nr_scanned++;
> try_to_free_pages() always sets it. > > try_to_free_mem_cgroup_pages() sets it depending on whether it really > wants swapping, and only swapping, right? right.
> But the above would still reclaim already swapped anon pages then, it would be better to add a check at shrink_page_list anyway..
Kosaki-san, what do you think?
Thanks, Daisuke Nishimura.
> and I don't know the memory > controller. > > balance_pgdat() always sets it. > > __zone_reclaim() sets it depending on zone_reclaim_mode. The > RECLAIM_SWAP bit of this field and its documentation in > Documentation/sysctl/vm.txt suggests it also really only means swap. > > shrink_all_memory() would be the sole user of may_unmap because it > really wants to eat cache first. But this could be figured out on a > different occasion. > > Hannes
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