On 29 Aug 2003 at 0:05, William Yu wrote:

> Shridhar Daithankar wrote:
> >> Be careful here, we've seen that with the P4 Xeon's that are
> >>hyper-threaded and a system that has very high disk I/O causes the
> >>system to be sluggish and slow. But after disabling the hyper-threading
> >>itself, our system flew..
> > 
> > Anybody has opteron working? Hows' the performance?
> Yes. I'm using an 2x 1.8GHz Opteron system w/ 8GB of RAM. Right now, I'm 
> still using 32-bit Linux -- I'm letting others be the 64-bit guinea 
> pigs. :) I probably will get a cheapie 1x Opteron machine first and test 
> the 64-bit kernel/libraries thoroughly before rolling it out to production.

Just a guess here but does a precompiled postgresql for x86 and a x86-64 
optimized one makes difference?

Opteron is one place on earth you can watch difference between 32/64 bit on 
same machine. Can be handy at times..

> As for performance, the scaling is magnificient -- even when just using 
> PAE instead of 64-bit addressing. At low transaction counts, it's only 
> ~75% faster than the 2x Athlon 1800+ MP it replaced. But once the 
> transactions start coming in, the gap is as high as 5x. My w-a-g: since 
> each CPU has an integrated memory controller, you avoid memory bus 
> contention which is probably the major bottleneck as transaction load 
> increases. (I've seen Opteron several vs Xeon comparisons where 
> single-connection tests are par for both CPUs but heavy-load tests favor 
> the Opteron by a wide margin.) I suspect the 4X comparisons would tilt 
> even more towards AMD's favor.

I am sure. But is 64 bit environment, Xeon is not the compitition. It's PA-RSC-
8700, ultraSparcs, Power series and if possible itanium.

I would still expect AMD to compete comfortably given high clock speed. But 
chipset need to be competent as well..

I still remember the product I work on, a single CPU PA-RISC 8700 with single 
SCSI disc, edged out a quad CPU Xeon with SCSI RAID controller running windows 
in terms of scalability while running oracle.

I am not sure if it was windows v/s HP-UX issue but at the end HP machine was 
lot better than windows machine. Windows machine shooted ahead for light load 
and drooeed dead equally fast with rise in load..
> We should see a boost when we move to 64-bit Linux and hopefully another 
> one when NUMA for Linux is production-stable.

Getting a 2.6 running now is the answer to make it stable fast..:-) Of course 
if you have spare hardware..


briefcase, n:   A trial where the jury gets together and forms a lynching party.

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