Re: Performance issues in 64-bit platforms
On Tuesday 20 March 2007 17:20, Lennart Sorensen wrote:
> > -------------------------------------------------------------------------
> >---------------------------------- 1 - LAPTOP:
> > /dev/sda:
> > Timing cached reads: 5788 MB in 1.99 seconds = 2901.82 MB/sec
> > Timing buffered disk reads: 102 MB in 3.02 seconds = 33.78 MB/sec
>
> 33MB/s sounds right for a decent laptop drive.
>
> Very nice ram speed on that (cached reads are a memory speed test, not a
> disk speed test).
>
Yes, of course.
> The memory performance is actually pathetic for an AMD. Are you running
> single channel by any chance? Dual channel memory should get about
> twice that (at least my old single core 3500+ with DDR400 does gets
> 1700MB/s or so). Make sure you are using a pair of identical memory
> modules and that they are installed into each channel. Using crap
> DDR2-533 ram is just a bad idea of course since that will really reduce
> memory performance even further. But you certainly want to be using
> dual channel.
Its dual channel, all right. 4 completely identical Crucial Ballistix 512MB
modules covering all available slots. The BIOS reports: 2G DDR400, Dual
channel, 128-bit.
> It sounds like dual channel on the laptop and single channel on the
> desktop. If the desktop isn't the new socket AM2 and using plain DDR
> ram, then your numbers make sense for single channel memory (they are
> absolutely wrong if you have two channels of memory).
The desktop is socket939, bought it 11/2005.
> > 2) Shouldn't the "notorious" WD raptor greatly outperform the Seagate
> > when comparing single disk performance (case 3 vs. 4)? After all, the WD
> > costs 2 times the price of the Seagate (or was it even more..?).
>
> On seek time and random acces, yes. On raw transfer rate no. The
> density and hence the amount of data moving past the head in a given
> amount of time is not great. After all if you run half the density at
> twice the speed, you still get the same amount of data going past the
> head.
That's true, thanx for pointing it out.
Dimitris
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