From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 5AB336B0055 for ; Mon, 20 Jul 2009 10:31:00 -0400 (EDT) Date: Mon, 20 Jul 2009 23:30:48 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH 4/5] Use add_page_to_lru_list() helper function In-Reply-To: <1248074911.15751.8023.camel@twins> References: <20090720143352.747E.A69D9226@jp.fujitsu.com> <1248074911.15751.8023.camel@twins> Message-Id: <20090720231618.AF69.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Peter Zijlstra Cc: kosaki.motohiro@jp.fujitsu.com, LKML , linux-mm , Andrew Morton List-ID: > On Mon, 2009-07-20 at 14:37 +0900, KOSAKI Motohiro wrote: > > > > @@ -1241,7 +1241,6 @@ static void move_active_pages_to_lru(str > > > > spin_lock_irq(&zone->lru_lock); > > > > } > > > > } > > > > - __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); > > > > if (!is_active_lru(lru)) > > > > __count_vm_events(PGDEACTIVATE, pgmoved); > > > > } > > > > > > This is a net loss, you introduce pgmoved calls to __inc_zone_state, > > > instead of the one __mod_zone_page_state() call. > > > > max pgmoved is 32. 32 times __inc_zone_state() make 0 or 1 time > > atomic operation (not much than two). > > I don't think it reduce performance. > > its not just atomics, count calls and branches too. It simply adds a ton > of code for no particular reason. hm, I don't think it's tons penalty. I mean vmscan makes tons cache miss and function calling penalty is hidden by it. But, I agreed this patch doesn't have strong motivation. I can drop this. Andrew, Can you please drop this patch? -- 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