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Re: removing an ext2fs file forces disk activity


From: Diego Roversi
Subject: Re: removing an ext2fs file forces disk activity
Date: Tue, 26 Mar 2002 22:47:54 +0100
User-agent: Mutt/1.2.5i

On Tue, Mar 26, 2002 at 12:55:19PM -0800, Thomas Bushnell, BSG wrote:
> nisse@lysator.liu.se (Niels Möller) writes:
> 
> > Perhaps idling, waiting for disk i/o requests to complete?
> 
> Do a big tar extraction on Linux and note that your tar process soaks
> up plenty of CPU time. 

I tried it, but it doesn't seem to do so:

$ tar cf /tmp/x.tar /usr/src/linux
tar: Removing leading `/' from member names

real    0m45.803s
user    0m0.260s
sys     0m2.370s

It looks like there is less than 1% of cpu time used by tar. And about 3% of
cpu time spent in kernel code.

In some my simple benchmarking, I have found that hurd is 5-10 times slowest
than linux in fs access. For example using bonnie++, a benchmark born to
stress filesystems, shows that while linux have a slow cpu utilisation,
usually <5%, hurd is using always a lot of cpu. 

And doing some tweaking in the ext2fs translator, I found that caching of
data is often inconsisten. I mean, rerunning the same test program that made
always the same file access, sometimes made disk access and sometimes not.

I always wondered why...

-- 
Saluti / Regards

Diego Roversi | 
              | diegor at tiscalinet.it 



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