Re: 2.6.4 : 100% CPU use on EIDE disk operarion, VIA chipset

[Bill Davidsen <davidsen@tmr.com>]

Mikhail Ramendik wrote:
> Hello,
> 
> Andreas Hartmann wrote:
> 
>>>As recommended there, I have tried 2.6.5-rc3-mm4.
>>>
>>>No change. Still 100% CPU usage; the performance seems teh same.
>>
>>Yes. But it's curious:
>>Take a tar-file, e.g. tar the compiled 2.6 kernel directory. Than, untar 
>>it again - the machine behaves total normaly. 
> 
> 
> Not really. I tried a "simple" tar (no gzib/bzip2) - it was the same as
> with cp, a near-100% CPU "system" load, most of it iowait.

??? was it in system or wait-io? One or the other, if you can't tell the 
difference update your tools, see what's really happening.
> 
> If I use bzip2 with tar, then yes, the load is nearly 100% "user",
> actually it's bzip2. But this is because the disk i/o is done at a *far*
> slower rate; the bottleneck is the CPU. If we don't read (or write) the
> disk heavily, naturally the system/iowait load is low.
> 
> I tried doing a "cp" in another xterm window, while the tar/bzip2 was
> running. And sure enough, up the CPU system/iowait usage goes - the
> "cp"'s disk i/o takes much of the CPU time away from the bz2 task! Looks
> exactly like a cause of performance problems.
> 
> (All of this was done on 2.6.5-rc3-mm4).

-- 
bill davidsen <davidsen@tmr.com>
   CTO TMR Associates, Inc
   Doing interesting things with small computers since 1979