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Date: Tue, 4 Jun 2013 14:07:44 +0900 From: Minchan Kim <minchan@...nel.org> To: Hillf Danton <dhillf@...il.com> Cc: Dave Hansen <dave@...1.net>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, akpm@...ux-foundation.org, mgorman@...e.de, tim.c.chen@...ux.intel.com Subject: Re: [v5][PATCH 5/6] mm: vmscan: batch shrink_page_list() locking operations On Tue, Jun 04, 2013 at 09:17:26AM +0800, Hillf Danton wrote: > On Tue, Jun 4, 2013 at 4:02 AM, Dave Hansen <dave@...1.net> wrote: > > +/* > > + * pages come in here (via remove_list) locked and leave unlocked > > + * (on either ret_pages or free_pages) > > + * > > + * We do this batching so that we free batches of pages with a > > + * single mapping->tree_lock acquisition/release. This optimization > > + * only makes sense when the pages on remove_list all share a > > + * page_mapping(). If this is violated you will BUG_ON(). > > + */ > > +static int __remove_mapping_batch(struct list_head *remove_list, > > + struct list_head *ret_pages, > > + struct list_head *free_pages) > > +{ > > + int nr_reclaimed = 0; > > + struct address_space *mapping; > > + struct page *page; > > + LIST_HEAD(need_free_mapping); > > + > > + if (list_empty(remove_list)) > > + return 0; > > + > > + mapping = page_mapping(lru_to_page(remove_list)); > > + spin_lock_irq(&mapping->tree_lock); > > + while (!list_empty(remove_list)) { > > + page = lru_to_page(remove_list); > > + BUG_ON(!PageLocked(page)); > > + BUG_ON(page_mapping(page) != mapping); > > + list_del(&page->lru); > > + > > + if (!__remove_mapping(mapping, page)) { > > + unlock_page(page); > > + list_add(&page->lru, ret_pages); > > + continue; > > + } > > + list_add(&page->lru, &need_free_mapping); > > + } > > + spin_unlock_irq(&mapping->tree_lock); > > + > While reclaiming pages, can we open ears upon IRQ controller, > if the page list length is over 10, or even 20? At the moment, it implicitly could be bounded by SWAP_CLUSTER_MAX and it's the value used by isolate_migratepages_ranges to enable IRQ. I have no idea it's proper value to give a chace to IRQ but at least, Dave's code doesn't break the rule. If we need a tune for that, it could be a another patch to investigate all of places on vmscan.c in near future. > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@...ck.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a> -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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