What is a good lap top

David J. Looney dlooney at attglobal.net
Sun Jun 20 22:06:20 PDT 2004


On Sun, 20 Jun 2004 13:50:46 -0700
"Andrew P. Lentvorski, Jr." <bsder at mail.allcaps.org> wrote:


[used date to echo time, run command, and then date again]

> 
> Here's how I tend to check drive speed:
> 
> Andrew-Lentvorskis-Computer:~/pymahjongg/src andrewl$ dd if=/dev/zero 
> of=/tmp/junkfile
> <hit control-c when you think you have written enough junk to the
> file> 247853+0 records in
> 247853+0 records out
> 126900736 bytes transferred in 4.928291 secs (25749440 bytes/sec)
> Andrew-Lentvorskis-Computer:~/pymahjongg/src andrewl$

What version/distribution of dd gives you elapsed time like this ? Or do
you have dd aliased to some additional commands ?

My dd doesn't, though using 'time' would make more sense, e.g.: 

> time dd if=/dev/zero of=/media/sda1/test/junk.dat        
1205729+0 records in
1205728+0 records out

real 25.27
user 0.68
sys 9.04

Or about 24.4 Mb/sec.  But using dd, copy speed seems very dependent on
blocksize, e.g. with bs=1 (I think dd defaults to 512), I get only 0.23
Mb/sec transfer, at bs=128 20.7 Mb/sec, at bs=512 25.5 Mb/sec, at 1024
as above.

Dave Looney 

-- 
The only intuitive interface is the nipple. After that, it is all
learned. - Bruce Ediger,Jay Vollmer



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