From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <43D03A48.8090105@jp.fujitsu.com> Date: Fri, 20 Jan 2006 10:18:00 +0900 From: KAMEZAWA Hiroyuki MIME-Version: 1.0 Subject: Re: [PATCH 0/5] Reducing fragmentation using zones References: <20060119190846.16909.14133.sendpatchset@skynet.csn.ul.ie> <43CFE77B.3090708@austin.ibm.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Mel Gorman Cc: Joel Schopp , linux-mm@kvack.org, linux-kernel@vger.kernel.org, lhms-devel@lists.sourceforge.net List-ID: Mel Gorman wrote: > To satisfy this request, I did a quick rebase of the list-based approach > against 2.6.16-rc1-mm1 to have a comparable set of benchmarks. I will post > the patches in the morning after a re-read. > Thank you. > So, in terms of performance on this set of tests, both approachs perform > roughly the same as the stock kernel in terms of absolute performance. In > terms of high-order allocations, zone-based appears to do better under > load. However, if you look at the zones that are used, you will see that > zone-based appears to do as well as list-based *only* because it has the > EASYRCLM zone to play with. list-based was way better at keeping the > normal zone defragmented as well as highmem which is especially obvious > when tested at rest. list-based was able to allocate 83 huge pages from > ZONE_NORMAL at rest while zone-based only managed 8. > yes, this is intersiting point :) list-based one can defrag NORMAL zone. The point will be "does we need to defrag NORMAL ?" , I think. IMHO, I don't like to use NORMAL zone to alloc higher-order pages... > Secondly, zone-based requires careful configuration to be successful. If > booted with kernelcore=896MB for example, it only performs slightly better > than the standard kernel. If booted with kernelcore=1024MB, it tends to > perform slightly worse (more zone fallbacks I guess) and still only > manages slighly better satisfaction of high order pages. This is because HIGHMEM is too small, right ? > On the flip side, zone-based code changes are easier to understand than > the list-based ones (at least in terms of volume of code changes). The > zone-based gives guarantees on what will happen in the future while > list-based is best-effort. > > In terms of fragmentation, I still think that list-based is better overall > without configuration. I agree here. >The results above also represent the best possible > configuration with zone-based versus no configuration at all against > list-based. In an environment with changing workloads a constant reality, > I bet that list-based would win overall. > On x86, NORMAL is only 896M anyway. there is no discussion. Honestly, I don't have enough experience with machines which doesn't have Highmem. How large kernelcore should be ? It looks using list-based and zone-based at the same time will make all people happy... -- Kame -- 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