From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 10 Mar 2006 12:59:21 -0800 (PST) From: Christoph Lameter Subject: drain_node_pages: interrupt latency reduction / optimization Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: akpm@osdl.org Cc: linux-mm@kvack.org List-ID: 1. Only disable interrupts if there is actually something to free 2. Only dirty the pcp cacheline if we actually freed something. 3. Disable interrupts for each single pcp and not for cleaning all the pcps in all zones of a node. drain_node_pages is called every 2 seconds from cache_reap. This fix should avoid most disabling of interrupts. Signed-off-by: Christoph Lameter Index: linux-2.6/mm/page_alloc.c =================================================================== --- linux-2.6.orig/mm/page_alloc.c 2006-03-10 10:34:56.000000000 -0800 +++ linux-2.6/mm/page_alloc.c 2006-03-10 12:55:02.000000000 -0800 @@ -599,7 +599,6 @@ void drain_node_pages(int nodeid) int i, z; unsigned long flags; - local_irq_save(flags); for (z = 0; z < MAX_NR_ZONES; z++) { struct zone *zone = NODE_DATA(nodeid)->node_zones + z; struct per_cpu_pageset *pset; @@ -609,11 +608,14 @@ void drain_node_pages(int nodeid) struct per_cpu_pages *pcp; pcp = &pset->pcp[i]; - free_pages_bulk(zone, pcp->count, &pcp->list, 0); - pcp->count = 0; + if (pcp->count) { + local_irq_save(flags); + free_pages_bulk(zone, pcp->count, &pcp->list, 0); + pcp->count = 0; + local_irq_restore(flags); + } } } - local_irq_restore(flags); } #endif -- 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