[GRLUG] Solid State Drives

[Collin Kidder]

David Pembrook wrote:
> Collin Kidder wrote:
>   
>> Tim Schmidt wrote:
>>   
>>     
>>> On Mon, Dec 1, 2008 at 3:32 PM, Collin Kidder <adderd at kkmfg.com> wrote:
>>>   
>>>     
>>>       
>>>> Swap might be a bit faster than file system access but can't be faster
>>>> than the maximum throughput of the drive(s).
>>>>     
>>>>       
>>>>         
>>> Yes, it can.  It's called compression.  Often used in situations where
>>> one might want to shove a large amount of data over a low bandwidth
>>> link.  Mainline Linux kernels don't compress swap (yet), but it's
>>> certainly a feature I'd expect to see sometime.
>>>
>>> --tim
>>>   
>>>     
>>>       
>> Yes, it will probably be included at some point. Compression is CPU 
>> bound though.
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>>   
>>     
> well in many cases we're io bound not cpu bound. So we have a system 
> that adapts?
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Actually that is the beauty of it. A compressed swap would transfer some 
of the bandwidth cost to the CPU instead of the hard drive. If, say, the 
harddrive can maintain 60MB/s and the CPU can compress to half size then 
you effectively get 120MB/s throughput. In a fast multicore machine 
(which is common nowdays) the CPU usage is a pretty small concern.