from the 64-bits-and-some-buts dept.
This morning, 05:35, I got an SMS. Not the one from my dancing partner I expected but from our BigBrother. Three of our new Athlon64 who scans for viiri and spam went down. We deployed 5 of them during the last two weeks and like to share our experience with you. Read on if you like to buy or operate an Opteron or Athlon64 based system.
Compared to Intel, which developed a complete new CPU called Itanium, AMD decided to enhance the existing i386 instruction set. An Athlon64 or Opteron based system - we call them from now on x86_64 - is compatible to any operating system which is running on IBM compatible PCs. So you may run DOS, any kind of Windows, Linux/i386 and others. There is no need to buy a non-x86_64 when you need a new computer. There is also no need to install a dedicated 64 bit operating system.
But, first of all, way should you use 64 bits? As short FAQ:
So let's install a true 64 bit operating system. Linux is available since a long time, but the distributions are still far away from beeing perfect:
Debian, our favorite distribution, has no true 64 bit support in Sarge and Sid. The stable i386 version works well. You will need Knoppix and debootstrap to install Woody - the current install medias would not boot.
Gentoo has a working 64 bit version for x86_64. Because of the large administration overhead, we cant use it.
Fedora has a working x86_64 port and is the only free available distribution which also supports 32 bits binarys on the fly. Like in Solaris, HP-UX, AIX or Irix, you'll find a /lib and /lib64, /usr/lib and /usr/lib64. We are using Fedora on our virus scanners to get all performance out of the CPU for Spamassassin, amavisd-new and ClamAV but also support uvscan which is a closed source 32 bit binary.
AMD invested a lot of money and manpower in the development of gcc, the GNU C Compiler. Modern gcc compilers produce highly optimized code for x86_64 which performs much better then i386 code on the same platform. A non-representative-benchmark (openssl speed rsa512) shows, that a recent Athlon is twice as fast as a PIV, 32 bits code on a Athlon64 is twice as fast as on the Athlon and 64 bits code on a Athlon64 is twice as fast as 32 bits code on a Athlon64. (don't trust any statistics you did'nt forge yourself :-)
On the other hand, the mixed mode of 32 and 64 bits is not as stable as it could be. Fedora's current Kernel 2.6.8-1.521 has a large memory leak when executing 32 bits code and was responsible for the SMS this morning.
Windows is available as a public Beta. We installed this system on one of our boxes for testing. It seems to work, but near every piece of hardware is still missing some drivers. Even more, there are currently two versions of Windows XP 64 Bit: One for Athlon64 and one for Itanium. Microsoft does not yet point at this difference, so be sure to get the right version! Applications are no problem - it seems to be possible to run near every application written for Win32.
Intel is also incorporating AMDs 64 bit instruction set in their Pentium IV and Xeon systems. Intel call this Extended Memory 64 Technology EM64T. It would be nice to view the benchmarks between AMD and Intel CPUs.
Our conclusion: Athlon64 is a fine CPU. Dont hesitate to buy and use one. But to use the whole power of the 64 bits, you shuld have a lot of knowledge or some time to wait.
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