Re: swap prefetching merge plans

[Helge Hafting <helge.hafting@aitel.hist.no>]

Hemmann, Volker Armin wrote:

>On Thursday 23 March 2006 12:47, you wrote:
>  
>
>>On Thursday 23 March 2006 10:26, Nick Piggin wrote:
>>    
>>
>>>Hemmann, Volker Armin wrote:
>>>      
>>>
>>>>Hi,
>>>>
>>>>I am just a user, but I would love to see this feature.
>>>>
>>>>After compiling stuff, I have usually some kb in swap (300kb, 360 kb),
>>>>and lots of free ram. But even this few kb make my KDE desktop extremly
>>>>sluggish. It feels, like every byte is fetched individually and always
>>>>the wrong stuff ends in swap.
>>>>        
>>>>
>>>I'm almost positive this wouldn't be the cause of your problems (even a
>>>slow disk could read all these blocks in, randomly, in under 2 seconds,
>>>assuming they're spread from one end of the platters to the other).
>>>      
>>>
>>Maybe he meant 300 megabytes.
>>    
>>
>
>no, I meant kilobytes.
>
>And swapoff really helps.
>
>Some moments of disk activity, and bang, computer is as fast as always again.
>
>But having stuff in swap? konqueror is slow, kmail is slow, opening a konsole 
>session, slow. Everything crawls with lots of disk access. 
>
>next time the computer is slow, I could gather some data - if you tell me, 
>what is interessting for you, I'll save it.
>  
>
Strange indeed.  300k in swap is nothing - I often enough
have 50M in swap without a slowdown - but then, I don't
run kde. 

Be aware that the 300k in swap doesn't account for all that
is removed from memory.  Linux don't put executable code
in swap - such stuff is simply dropped because it can
be reloaded from the executable files anytime.
I don't think swapoff+swapon helps with that though.

Helge Hafting