The SPUs seem to become VERY irrealistic

Gerard Beekmans gerard at linuxfromscratch.org
Fri Oct 18 16:31:11 PDT 2002


On October 18, 2002 03:25 pm, Florian Hess (FLoH) wrote:
> measurement of 1 SPU = 892sec is no more realistic at all. The

SBUs can't really be seen as linear numbers due to all kinds of external 
factors (such as Matthias already explained). The SBU average still works out 
in most cases but you have a very old system which is a lot slower than most 
of the ones we tested SBU averages on. We're still talking about averages. 
The point is, that for a faster system the averages will differ a few 
minutes. But the slower a system gets, the bigger the average differences 
get. For your machine 2 extra hours is about right

> The dma mode has been activated at 10:00p, but he doesn't seem to 
> accelerate the compilation.

That means for 3.5 hours you didn't have DMA enabled. Not enabling DMA makes a 
harddrive very slow. In my machine not using DMA hdparm shows a throughput of 
7 MB/sec and with DMA  46 MB/sec . That's quite a difference.

During a GCC installation a lot of files are written to your disk. If DMA is 
disabled all those write operations take a lot longer.

Try this when you some time: enable DMA right from the start and try a GCC 
installation again. Maybe the estimated during of 2.5 hours may be closer to 
what you will get.

Or try the next big package, Glibc, later on and see how it does (make sure 
that you run hdparm to turn on DMA. I'd put it in a bootscript so you never 
forget to do so).

-- 
Gerard Beekmans
www.linuxfromscratch.org

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