From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752514AbcFCKKR (ORCPT ); Fri, 3 Jun 2016 06:10:17 -0400 Received: from mx2.suse.de ([195.135.220.15]:54915 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751579AbcFCKKP (ORCPT ); Fri, 3 Jun 2016 06:10:15 -0400 Subject: Re: [PATCH v2 1/7] mm/compaction: split freepages without holding the zone lock To: js1304@gmail.com, Andrew Morton References: <1464230275-25791-1-git-send-email-iamjoonsoo.kim@lge.com> Cc: mgorman@techsingularity.net, Minchan Kim , Alexander Potapenko , Hugh Dickins , Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Joonsoo Kim From: Vlastimil Babka Message-ID: Date: Fri, 3 Jun 2016 12:10:10 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 MIME-Version: 1.0 In-Reply-To: <1464230275-25791-1-git-send-email-iamjoonsoo.kim@lge.com> Content-Type: text/plain; charset=iso-8859-2; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/26/2016 04:37 AM, js1304@gmail.com wrote: > From: Joonsoo Kim > > We don't need to split freepages with holding the zone lock. It will cause > more contention on zone lock so not desirable. > > Signed-off-by: Joonsoo Kim So it wasn't possible to at least move this code from compaction.c to page_alloc.c? Or better, reuse prep_new_page() with some forged gfp/alloc_flags? As we discussed in v1... > --- > include/linux/mm.h | 1 - > mm/compaction.c | 42 ++++++++++++++++++++++++++++++------------ > mm/page_alloc.c | 27 --------------------------- > 3 files changed, 30 insertions(+), 40 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index a00ec81..1a1782c 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -537,7 +537,6 @@ void __put_page(struct page *page); > void put_pages_list(struct list_head *pages); > > void split_page(struct page *page, unsigned int order); > -int split_free_page(struct page *page); > > /* > * Compound pages have a destructor function. Provide a > diff --git a/mm/compaction.c b/mm/compaction.c > index 1427366..8e013eb 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -65,13 +65,31 @@ static unsigned long release_freepages(struct list_head *freelist) > > static void map_pages(struct list_head *list) > { > - struct page *page; > + unsigned int i, order, nr_pages; > + struct page *page, *next; > + LIST_HEAD(tmp_list); > + > + list_for_each_entry_safe(page, next, list, lru) { > + list_del(&page->lru); > + > + order = page_private(page); > + nr_pages = 1 << order; > + set_page_private(page, 0); > + set_page_refcounted(page); > + > + arch_alloc_page(page, order); > + kernel_map_pages(page, nr_pages, 1); > + kasan_alloc_pages(page, order); > + if (order) > + split_page(page, order); > > - list_for_each_entry(page, list, lru) { > - arch_alloc_page(page, 0); > - kernel_map_pages(page, 1, 1); > - kasan_alloc_pages(page, 0); > + for (i = 0; i < nr_pages; i++) { > + list_add(&page->lru, &tmp_list); > + page++; > + } > } > + > + list_splice(&tmp_list, list); > } > > static inline bool migrate_async_suitable(int migratetype) > @@ -368,12 +386,13 @@ static unsigned long isolate_freepages_block(struct compact_control *cc, > unsigned long flags = 0; > bool locked = false; > unsigned long blockpfn = *start_pfn; > + unsigned int order; > > cursor = pfn_to_page(blockpfn); > > /* Isolate free pages. */ > for (; blockpfn < end_pfn; blockpfn++, cursor++) { > - int isolated, i; > + int isolated; > struct page *page = cursor; > > /* > @@ -439,13 +458,12 @@ static unsigned long isolate_freepages_block(struct compact_control *cc, > goto isolate_fail; > } > > - /* Found a free page, break it into order-0 pages */ > - isolated = split_free_page(page); > + /* Found a free page, will break it into order-0 pages */ > + order = page_order(page); > + isolated = __isolate_free_page(page, page_order(page)); > + set_page_private(page, order); > total_isolated += isolated; > - for (i = 0; i < isolated; i++) { > - list_add(&page->lru, freelist); > - page++; > - } > + list_add_tail(&page->lru, freelist); > > /* If a page was split, advance to the end of it */ > if (isolated) { > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d27e8b9..5134f46 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2525,33 +2525,6 @@ int __isolate_free_page(struct page *page, unsigned int order) > } > > /* > - * Similar to split_page except the page is already free. As this is only > - * being used for migration, the migratetype of the block also changes. > - * As this is called with interrupts disabled, the caller is responsible > - * for calling arch_alloc_page() and kernel_map_page() after interrupts > - * are enabled. > - * > - * Note: this is probably too low level an operation for use in drivers. > - * Please consult with lkml before using this in your driver. > - */ > -int split_free_page(struct page *page) > -{ > - unsigned int order; > - int nr_pages; > - > - order = page_order(page); > - > - nr_pages = __isolate_free_page(page, order); > - if (!nr_pages) > - return 0; > - > - /* Split into individual pages */ > - set_page_refcounted(page); > - split_page(page, order); > - return nr_pages; > -} > - > -/* > * Update NUMA hit/miss statistics > * > * Must be called with interrupts disabled. >