Date: Fri, 7 Dec 2007 16:21:16 -0500 From: Adam McDougall <mcdouga9@egr.msu.edu> To: Pete French <petefrench@ticketswitch.com> Cc: freebsd-stable@FreeBSD.ORG Subject: Re: Also seeing 2 x quad-core system slower that 2 x dual core Message-ID: <20071207212115.GQ1014@egr.msu.edu> In-Reply-To: <E1J0cUE-000CkR-6X@dilbert.ticketswitch.com> References: <E1IxklH-000ElU-3w@dilbert.ticketswitch.com> <E1J0cUE-000CkR-6X@dilbert.ticketswitch.com>
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On Fri, Dec 07, 2007 at 12:39:22PM +0000, Pete French wrote: Just as a followup to this - I soent some time going through all the suggestions and advice that people gave me regarding this problem. It turns out that the newer servers shipped by HP have different cache settings to the older ones on their RAID controllers, plus I get very different results from my benchmarks depending on how long the machines have been booted for and what activity has occurred on them (probably due to things ending up in cache). Upshot - if the machines are configured identically, and an identical install is made and an identical test doen then we get identical performance as expected. Part of the reason for posting this though is that a lot of people have bbeen worrying about 8x CPU performance, and this thread won't have helped. So I wanted to say that now I am convinced that (for my workload) these machines are fine. To the point where I have installed 7.0-BETA4 on the ten new 8 core servers for a very large load on th webfarm this morning. I'm pleased toio say that it went off perfectly, the servers took the load and we had no problems at all. We are running CGI scripts against mySQL under apache22 basically - which is a pretty common thing to do. Ia m using ULE and tthe amd64 version of the OS. 7.0 is excellent as far as I am concerned, and I don't think people should be worried about deploying it on 8 core machines. My experinec has been that it is fine and is also somewhat faster than 6.3 on the same hardware. -pete. I feel I have to throw in my experience too just for the archives. This previous weekend I had the opportunity to play with a dual quad-core dell precision 690, and I saw no huge performance problems. All around I was fairly happy with standard compile tests, did some rm. I didn't do anything involved like databases or php. I could do a buildkernel with a few additional kernel modules in 29 seconds :) but buildworld doesn't seem to benefit much from -j16 on a 8 core (not unexpected). I didn't have any useful parallel loads to test on it.
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