From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932666AbWFMAI3 (ORCPT ); Mon, 12 Jun 2006 20:08:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932668AbWFMAI3 (ORCPT ); Mon, 12 Jun 2006 20:08:29 -0400 Received: from omx1-ext.sgi.com ([192.48.179.11]:12731 "EHLO omx1.americas.sgi.com") by vger.kernel.org with ESMTP id S932666AbWFMAI2 (ORCPT ); Mon, 12 Jun 2006 20:08:28 -0400 Date: Mon, 12 Jun 2006 17:08:07 -0700 (PDT) From: Christoph Lameter To: Con Kolivas cc: linux-kernel@vger.kernel.org, akpm@osdl.org, Hugh Dickins , Marcelo Tosatti , Nick Piggin , linux-mm@kvack.org, Andi Kleen , Dave Chinner Subject: Re: [PATCH 19/21] swap_prefetch: Conversion of nr_unstable to ZVC In-Reply-To: <200606130959.48006.kernel@kolivas.org> Message-ID: References: <20060612211244.20862.41106.sendpatchset@schroedinger.engr.sgi.com> <200606130957.28414.kernel@kolivas.org> <200606130959.48006.kernel@kolivas.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 13 Jun 2006, Con Kolivas wrote: > The comment should read something like: If we need another round then maybe it would be best if you would do that patch. This? Subject: swap_prefetch: conversion of nr_unstable to per zone counter From: Christoph Lameter The determination of the vm state is now not that expensive anymore after we remove the use of the page state. Change the logic to avoid the expensive checks. Signed-off-by: Christoph Lameter Signed-off-by: Con Kolivas Index: linux-2.6.17-rc6-cl/mm/swap_prefetch.c =================================================================== --- linux-2.6.17-rc6-cl.orig/mm/swap_prefetch.c 2006-06-12 13:37:47.283159568 -0700 +++ linux-2.6.17-rc6-cl/mm/swap_prefetch.c 2006-06-12 17:06:44.875945042 -0700 @@ -298,7 +298,7 @@ static int prefetch_suitable(void) { unsigned long limit; struct zone *z; - int node, ret = 0, test_pagestate = 0; + int node, ret = 0; /* Purposefully racy */ if (test_bit(0, &swapped.busy)) { @@ -307,17 +307,15 @@ static int prefetch_suitable(void) } /* - * get_page_state and above_background_load are expensive so we only - * perform them every SWAP_CLUSTER_MAX prefetched_pages. + * above_background_load() is expensive so we only perform + * it every SWAP_CLUSTER_MAX prefetched_pages. * We test to see if we're above_background_load as disk activity * even at low priority can cause interrupt induced scheduling * latencies. */ - if (!(sp_stat.prefetched_pages % SWAP_CLUSTER_MAX)) { - if (above_background_load()) + if ((!(sp_stat.prefetched_pages % SWAP_CLUSTER_MAX)) && + above_background_load()) goto out; - test_pagestate = 1; - } clear_current_prefetch_free(); @@ -357,7 +355,6 @@ static int prefetch_suitable(void) */ for_each_node_mask(node, sp_stat.prefetch_nodes) { struct node_stats *ns = &sp_stat.node[node]; - struct page_state ps; /* * We check to see that pages are not being allocated @@ -375,11 +372,6 @@ static int prefetch_suitable(void) } else ns->last_free = ns->current_free; - if (!test_pagestate) - continue; - - get_page_state_node(&ps, node); - /* We shouldn't prefetch when we are doing writeback */ if (node_page_state(node, NR_WRITEBACK)) { node_clear(node, sp_stat.prefetch_nodes); @@ -394,7 +386,8 @@ static int prefetch_suitable(void) node_page_state(node, NR_ANON) + node_page_state(node, NR_SLAB) + node_page_state(node, NR_DIRTY) + - ps.nr_unstable + total_swapcache_pages; + node_page_state(node, NR_UNSTABLE) + + total_swapcache_pages; if (limit > ns->prefetch_watermark) { node_clear(node, sp_stat.prefetch_nodes); continue;