IT @ AnandTech: Linux Database Server CPU Comparison

Introduction

Enterprise versions of Linux based on kernel 2.6, and 64 bit database servers are now very mature. Dual core 64 bit Opteron and 64 bit Xeons with 2 MB L2-caches are available. It was definitely time to update our previous Linux Database Server CPU comparison.

In this article, you will find a comparison of the latest Xeon (Irwindale), the previous Xeon (Nocona), the old Xeon (Galatin), the Dual core Opteron, and the "normal" Opteron, of course. We also included the Pentium-D to get an idea of what a Dual core Xeon could do, although the comparison is not completely fair: the memory subsystem of a Dual core Xeon will have higher latency and slightly lower bandwidth as it will use ECC buffered DIMMs instead of non-buffered DIMMs.

In our previous article, we used SUSE SLES 8 (kernel 2.4.21) and the Xeon 3.6 GHz "Nocona" matched the performance of the Opteron 250 in 32 bit DB2, but failed to impress in MySQL. Intel's Xeon was not recognized as a 64 bit capable CPU by SLES 8 with kernel 2.4 however, and the Opteron gained 12% (DB2) and 30% (MySQL) when running in 64 bit.

On SLES 9, we can unleash the full 64 bit potential of both the Intel Xeon and Opteron. Kernel 2.6 includes better and improved support for NUMA, 64 bit, large memory pages, threading and fully recognizes EM64T CPUs as 64 bit capable. How do the Xeon and Opteron compare when they both run 64 bit applications on a 64 bit enterprise version of Linux? Should you invest in Dual core CPUs, or are these expensive CPUs beaten by two single CPUs? Should you wait for Dempsey, the dual core Xeon?

These are a few of the questions that we will answer. While we still continue to improve the quality of our benchmarks, we decided to report our first impressions.

The scope and focus of this test

Our last Database server comparison generated quite a bit of very useful and interesting feedback. Living up to the excellent AnandTech tradition, we have read them carefully and taken many suggestions to heart.

In a nutshell, the foci of this article are as follows:

Only CPU and CPU-chipset-memory database performance tests
Mostly Database reads
DB2 and MySQL on SUSE SLES 9 - Kernel 2.6.5
Database use of small and medium-sized enterprises
single and dual processing systems.

Our benchmark Quality assurance methods include:

Checking the disk activity with iostat and vmstat
Constant monitoring of the Client's CPU load, network load and memory usage
Tests were repeated at least 3 times
All tests were performed with two different clients: a Dual Opteron 850 2.4 GHz and a Quad Opteron 848 2.2 GHz
Improved and optimised Client program

Real world databases are in many cases disk limited. Jason and Ross have been running 8 x 36GB 15,000RPM Ultra320 SCSI drives in RAID-0 to avoid the Enterprise Class Performance tests being limited by disk I/O performance.

However, the Lab of the Technical University of Kortrijk where we performed our tests did not dispose of such an impressive disk array, and we were determined to focus on the database performance of the different CPUs and CPU-chipset-memory combinations. All tests were done (99% of the time) with in-memory queries. Investigating the performance of different disk storage systems is a time-consuming and completely different project.

We still tested with our 1 GB big database imported in MySQL MyISAM, InnoDB and IBM's DB2 8.2 .

Some of you might still be convinced that in-memory tests are not really relevant. Consider that the availability of cheap 64 bit system makes it possible to use much more RAM than before. Flat 64 bit addressing of more than 4 GB of RAM used to be a privilege of very expensive servers (Power4, etc.), but this is no longer the case with the introduction of Intel's EM64T Xeons and AMD's AMD64 Opteron.

With the current prices of 1 GB DDR(-II) sticks, it is very easy and inexpensive to build a database server with 8 GB of RAM. Even 16 GB (16x1 GB) is not that expensive, considering the price of a quad Opteron server. As a seasoned sys-admin told me, "the performance of database servers can be brought back to life with some extra RAM." It is in many cases that a large amount of RAM can do more than very expensive 15,000RPM SCSI disks.

Again, this article is not about the typical huge central databases of banks that need to handle a large number of transactions, with writes operations being very frequent.

We test on SUSE SLES 9 (SUSE Enterprise Edition) SP1, Linux kernel 2.6.5-151smp. Yes, this is not the latest kernel version, which is 2.6.12 at the time of this article. We used 2.6.5 because it is the last kernel available for our enterprise version of SUSE. The very nature of this project also forces us to check our numbers with at least 5 consecutive tests, and a lot of time is spent in checking parameters and so on, so we need to "freeze" the kernel version for a few weeks. We did perform a few tests on Gentoo, however, with kernel version 2.6.12.