From: Christoph Lameter Date: Wed, 22 Mar 2006 08:09:08 +0000 (-0800) Subject: [PATCH] drain_node_pages: interrupt latency reduction / optimization X-Git-Tag: v2.6.17-rc1~1129^2~20 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=879336c3930ae9273ea1c45214cb8adae0ce494a;p=linux-2.6 [PATCH] drain_node_pages: interrupt latency reduction / optimization 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ed91684cb1..b7f14a4799 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -603,13 +603,14 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order, /* * Called from the slab reaper to drain pagesets on a particular node that * belong to the currently executing processor. + * Note that this function must be called with the thread pinned to + * a single processor. */ 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; @@ -619,11 +620,14 @@ 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