Messages in this thread | | | Date | Sat, 11 Apr 2009 11:49:20 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 6/9] readahead: clean up and simplify the code for filemap page fault readahead |
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On Sat, 11 Apr 2009 22:58:31 +0900 KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:
> > Ah. __But I have a note here that I didn't like it, because it adds lots > > of new spinlocking to fastpaths. __So I'll leave things as they stand > > until we have had a little talk about that. > > add? > > old code: grab zone->lru_lock via mark_page_accessed() > new code: grab zone->lru_lock via update_reclaim_stat() > > one remove, one add. >
mm-update_page_reclaim_stat-is-called-from-page-fault-path.patch adds new calls to update_page_reclaim_stat() into do_swap_page() and filemap_fault(). update_page_reclaim_stat() does spin_lock_irq() and spin_unlock_irq(). It looks like a net slowdown to me.
> But I agree its lock can be removed maybe..
It would be nice to try to do something about it - every little bit counts.
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