From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de (ns2.suse.de [195.135.220.15]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mx2.suse.de", Issuer "Thawte Premium Server CA" (verified OK)) by ozlabs.org (Postfix) with ESMTP id BD68067B44 for ; Wed, 7 Jun 2006 20:16:43 +1000 (EST) From: Andi Kleen To: Mel Gorman Subject: Re: [PATCH 0/5] Sizing zones and holes in an architecture independent manner V7 Date: Wed, 7 Jun 2006 12:16:24 +0200 References: <20060606134710.21419.48239.sendpatchset@skynet.skynet.ie> <200606071145.04938.ak@suse.de> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Message-Id: <200606071216.24640.ak@suse.de> Cc: Andrew Morton , davej@codemonkey.org.uk, tony.luck@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, bob.picco@hp.com, linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , > Right now, x86_64 seems to be the only arch that accounts for the kernel > image and memmap as holes so I would consider it to be unusual. s/unusual/more advanced/ > For memory > hot-add, new memmaps are allocated using kmalloc() and are not accounted > for as holes. At least in the standard (non sparsemem) hotadd they are accounted afaik. > So, on x86_64, some memmaps are holes and others are not. > > Why is it a performance regression if the image and memmap is accounted > for as holes? How are those regions different from any other kernel > allocation or bootmem allocations for example which are not accounted as > holes? They are comparatively big and cannot be freed. >If you are sure that it makes a measurable difference to performance, There was at least one benchmark/use case where it made a significant difference, can't remember the exact numbers though. -Andi