Advantages of 64-bitness for LAMP applications?

Hewitt Tech hewitt_tech at comcast.net
Thu Dec 23 10:03:00 EST 2004


I've put together a couple of AMD-64 based systems and in general they feel
"fast". The problem with that kind of an observation is that there's really
no data behind it. Recently Infoworld reviewed an IBM Opteron (the
commercial version of the AMD-64 family) and claimed that their testing
showed that for heavy multi-tasking operations, the IBM system didn't are
that well compared to Hyperthreaded Intel Xeon processor based systems. They
did say that for single thread of execution model processes, the Opteron was
the fastest X86 processor.

In the Linux world you can have an AMD-64 64 bit version of Linux from SuSe
and I would assume RedHat would have one but I've only seen press on the
SuSe version. Another issue would be that if you want 64 bit programs, you'd
mostly need to build from source although that's a great strength of OSS.

In a former life I worked at Digital/Compaq/HP in the UNIX group hosted on
Alpha hardware. That platform started out as 64 bit and almost everything
built for it was 64 bit. The areas where the Alpha dominated were search
engines, large database applications and genomics research. I saw reports
that it was a very competent web server as well. One of the first
demonstrations of what you could do with a 64 bit Alpha was a million record
sort on an Oracle database which took something like 60 seconds on the first
large memory Alphas. I believe that Oracle simply read the entire database
into memory and did the sort in core. They used 16 GB of RAM on the test
machine. The customers that really loved those machines were the national
labs and certain government agencies ;^).

Over the years that I worked on the platform we fixed numerous pointer
problems as well as lot's of lock and memory contention issues. There
weren't that many problems directly related to 64 bit operations although I
do remember and interesting file access problem that came about because a 32
bit operand was used in a > 4 GB file access. The fix was as simple as
changing the declaration of the variable and the speedup in performance was
very noticeable.

-Alex





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