From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 07 Feb 2008 10:20:39 +0900 From: KOSAKI Motohiro Subject: Re: [patch 05/19] split LRU lists into anon & file sets In-Reply-To: <20080206193512.77b5f21f@bree.surriel.com> References: <20080130175439.1AFD.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20080206193512.77b5f21f@bree.surriel.com> Message-Id: <20080207101634.4AC7.KOSAKI.MOTOHIRO@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Rik van Riel Cc: kosaki.motohiro@jp.fujitsu.com, Lee Schermerhorn , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Hi Rik Welcome back :) > > I found number of scan pages calculation bug. > > My latest version of get_scan_ratio() works differently, with the > percentages always adding up to 100. However, your patch gave me > the inspiration to (hopefully) find the bug in my version of the > code. OK. > > 2. wrong fraction omission > > > > nr[l] = zone->nr_scan[l] * percent[file] / 100; > > > > when percent is very small, > > nr[l] become 0. > > This is probably where the problem is. Kind of. > > I believe that the problem is that we scale nr[l] by the percentage, > instead of scaling the amount we add to zone->nr_scan[l] by the > percentage! Aahh, you are right. > Index: linux-2.6.24-rc6-mm1/mm/vmscan.c > =================================================================== > --- linux-2.6.24-rc6-mm1.orig/mm/vmscan.c 2008-02-06 19:23:16.000000000 -0500 > +++ linux-2.6.24-rc6-mm1/mm/vmscan.c 2008-02-06 19:22:55.000000000 -0500 > @@ -1275,13 +1275,17 @@ static unsigned long shrink_zone(int pri > for_each_lru(l) { > if (scan_global_lru(sc)) { > int file = is_file_lru(l); > + int scan; > /* > * Add one to nr_to_scan just to make sure that the > - * kernel will slowly sift through the active list. > + * kernel will slowly sift through each list. > */ > - zone->nr_scan[l] += (zone_page_state(zone, > - NR_INACTIVE_ANON + l) >> priority) + 1; > - nr[l] = zone->nr_scan[l] * percent[file] / 100; > + scan = zone_page_state(zone, NR_INACTIVE_ANON + l); > + scan >>= priority; > + scan = (scan * percent[file]) / 100; > + > + zone->nr_scan[l] += scan + 1; > + nr[l] = zone->nr_scan[l]; > if (nr[l] >= sc->swap_cluster_max) > zone->nr_scan[l] = 0; > else looks good. thank you clean up code. - kosaki -- 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