Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750810AbWHRHPf (ORCPT ); Fri, 18 Aug 2006 03:15:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750816AbWHRHPf (ORCPT ); Fri, 18 Aug 2006 03:15:35 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:51586 "EHLO fgwmail7.fujitsu.co.jp") by vger.kernel.org with ESMTP id S1750810AbWHRHPe (ORCPT ); Fri, 18 Aug 2006 03:15:34 -0400 Date: Fri, 18 Aug 2006 16:17:39 +0900 From: KAMEZAWA Hiroyuki To: Christoph Lameter Cc: manfred@colorfullife.com, ak@muc.de, mpm@selenic.com, marcelo@kvack.org, linux-kernel@vger.kernel.org, nickpiggin@yahoo.com.au, ak@suse.de, dgc@sgi.com Subject: Re: [MODSLAB 3/7] A Kmalloc subsystem Message-Id: <20060818161739.f7581645.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: References: <20060816022238.13379.24081.sendpatchset@schroedinger.engr.sgi.com> <20060816022253.13379.76984.sendpatchset@schroedinger.engr.sgi.com> <20060816094358.e7006276.ak@muc.de> <44E3FC4F.2090506@colorfullife.com> Organization: Fujitsu X-Mailer: Sylpheed version 2.2.0 (GTK+ 2.6.10; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1457 Lines: 36 On Thu, 17 Aug 2006 23:17:54 -0700 (PDT) Christoph Lameter wrote: > > So we only have a single lookup of vmem_map from memory in order to > calculate the address of struct page. The cacheline for vmem_map is > heavily used and certainly in memory. virt_to_page seems to be a very > efficient means to get to struct page. The problem scope may simply be > to minimize the cachelines touched during free and alloc. Just a note: with SPARSEMEM, we need more calculation and access to mem_section[] table and page structs(mem_map). > vmalloc_to_addr is certainly slower due to the page table walking. But the > user already is aware of the fact that vmalloc memory is not as fast as > direct mapped. Hmm. I wonder.... == vmalloc() area is backed-up by VHPT(16Kb page size). And direct-mapped-area is backed-up by software-tlb-miss-handler (16MB/64MB page size) If TLB misses frequently, prefetch will work well in virtually-mapped area (region5) rather direct-mapped-area (region 7) because of hardware assist of 'VHPT walker'. (just I think. I have no data) Considering some code walking through a list of objects scattered over all memory, Is virtually-mapped area really slow ? -Kame - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/