Re: 64-bit vs 32-bit performance ... backwards?

Installation of a 32-bit PostgreSQL on a 64-bit Linux like RHEL 4 is
very easy. Make sure that you have installed all needed 32-bit libs and
devel packages.

Here is an example to call configure to get a 32-bit PostgreSQL:

CXX="/usr/bin/g++ -m32" \
CPP="/usr/bin/gcc -m32 -E" \
LD="/usr/bin/ld -m elf_i386" \
AS="/usr/bin/gcc -m32 -Wa,--32 -D__ASSEMBLY__ -traditional" \
CC="/usr/bin/gcc -m32" \
CFLAGS="-O3 -funroll-loops -fno-strict-aliasing -pipe -mcpu=opteron
-march=opteron -mfpmath=sse -msse2" \
./configure --prefix=<pgsql-path>

J. Andrew Rogers schrieb:
> The short story is that for us 64-bit PostgreSQL on Opterons is
> typically something like 20% faster than 32-bit on the same, and *much*
> faster than P4 Xeon systems they nominally compete with. AMD64 is a
> more efficient architecture than x86 in a number of ways, and the
> Opteron has enviable memory latency and bandwidth that make it an
> extremely efficient database workhorse. x86->AMD64 is not a word-width
> migration, it is a different architecture cleverly designed to be
> efficiently compatible with x86. In addition to things like a more
> RISC-like register set, AMD64 uses a different floating point
> architecture that is more efficient than the old x87.
>

I did a few test in the past with 64-bit PostgreSQL and 32-bit
PostgreSQL and the 32-bit version was always faster.
Please find attached a small patch with does apply a change to the
x86_64 part also to the i386 part of src/include/storage/s_lock.h.
Without this change the performance of PostgreSQL 8.0 was horrible on a
Opteron. The effect is smaller with PostgreSQL 8.1.

Cheers
Sven.