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

[Bill Davidsen <davidsen@tmr.com>]

Andreas Hartmann wrote:
> Bill Davidsen wrote:
> 
>> Andreas Hartmann wrote:
>>
>>> This is what top says during cp of 512MB-file:
>>> Cpu(s):  2.0% us,  8.3% sy,  0.0% ni,  0.0% id, 89.0% wa,  0.7% hi,  
>>> 0.0% si
>>>
>>> New is "wa", what probably means "wait". This value is very high as 
>>> long as the HD is writing or reading datas:
>>>
>>> cp dummy /dev/null
>>> produces this top-line:
>>> Cpu(s):  3.0% us,  5.3% sy,  0.0% ni,  0.0% id, 91.0% wa,  0.7% hi,  
>>> 0.0% si
>>
>>
>> Yes "wa" is not intuitive, some other operating systems use "wio" for 
>> "wait i/o" time. As noted in the other thread, you can try the 
>> deadline elevator or increased readahead for your load.
> 
> 
> If the processor and the kernel could do other things during wa, like
> compiling e.g., it would be no problem. But it seems to be, that this is
> not possible. Or did I oversee something?

Yes, wio is similar to idle, processor is available for work even if 
disk access is running slowly.

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