From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 632C26B006A for ; Mon, 11 Jan 2010 01:40:26 -0500 (EST) Received: by yxe10 with SMTP id 10so16392930yxe.12 for ; Sun, 10 Jan 2010 22:40:24 -0800 (PST) Date: Mon, 11 Jan 2010 15:38:02 +0900 From: Minchan Kim Subject: Re: [PATCH 4/4] mm/page_alloc : relieve zone->lock's pressure for memory free Message-Id: <20100111153802.f3150117.minchan.kim@barrios-desktop> In-Reply-To: <1263191277-30373-1-git-send-email-shijie8@gmail.com> References: <1263184634-15447-4-git-send-email-shijie8@gmail.com> <1263191277-30373-1-git-send-email-shijie8@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Huang Shijie Cc: akpm@linux-foundation.org, mel@csn.ul.ie, kosaki.motohiro@jp.fujitsu.com, minchan.kim@gmail.com, linux-mm@kvack.org, Rik van Riel , Wu Fengguang , KAMEZAWA Hiroyuki List-ID: On Mon, 11 Jan 2010 14:27:57 +0800 Huang Shijie wrote: > Move the __mod_zone_page_state out the guard region of > the spinlock to relieve the pressure for memory free. > > Using the zone->lru_lock to replace the zone->lock for > zone->pages_scanned and zone's flag ZONE_ALL_UNRECLAIMABLE. > > Signed-off-by: Huang Shijie > --- > mm/page_alloc.c | 33 +++++++++++++++++++++++---------- > 1 files changed, 23 insertions(+), 10 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 290dfc3..dfd4be0 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -530,12 +530,9 @@ static void free_pcppages_bulk(struct zone *zone, int count, > { > int migratetype = 0; > int batch_free = 0; > + int free_ok = 0; > > spin_lock(&zone->lock); > - zone_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE); > - zone->pages_scanned = 0; > - > - __mod_zone_page_state(zone, NR_FREE_PAGES, count); > while (count) { > struct page *page; > struct list_head *list; > @@ -558,23 +555,39 @@ static void free_pcppages_bulk(struct zone *zone, int count, > page = list_entry(list->prev, struct page, lru); > /* must delete as __free_one_page list manipulates */ > list_del(&page->lru); > - __free_one_page(page, zone, 0, migratetype); > + free_ok += __free_one_page(page, zone, 0, migratetype); > trace_mm_page_pcpu_drain(page, 0, migratetype); > } while (--count && --batch_free && !list_empty(list)); > } > spin_unlock(&zone->lock); > + > + if (likely(free_ok)) { > + spin_lock(&zone->lru_lock); > + zone_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE); > + zone->pages_scanned = 0; > + spin_unlock(&zone->lru_lock); > + > + __mod_zone_page_state(zone, NR_FREE_PAGES, free_ok); > + } > } > > static void free_one_page(struct zone *zone, struct page *page, int order, > int migratetype) > { > - spin_lock(&zone->lock); > - zone_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE); > - zone->pages_scanned = 0; > + int free_ok; > > - __mod_zone_page_state(zone, NR_FREE_PAGES, 1 << order); > - __free_one_page(page, zone, order, migratetype); > + spin_lock(&zone->lock); > + free_ok = __free_one_page(page, zone, order, migratetype); > spin_unlock(&zone->lock); > + > + if (likely(free_ok)) { > + spin_lock(&zone->lru_lock); > + zone_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE); > + zone->pages_scanned = 0; > + spin_unlock(&zone->lru_lock); > + > + __mod_zone_page_state(zone, NR_FREE_PAGES, free_ok << order); > + } > } > > static void __free_pages_ok(struct page *page, unsigned int order) > -- > 1.6.5.2 > Thanks, Huang. Frankly speaking, I am not sure this ir right way. This patch is adding to fine-grained locking overhead As you know, this functions are one of hot pathes. In addition, we didn't see the any problem, until now. It means out of synchronization in ZONE_ALL_UNRECLAIMABLE and pages_scanned are all right? If it is, we can move them out of zone->lock, too. If it isn't, we need one more lock, then. Let's listen other mm guys's opinion. -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org