Re: Benchmark : ext3 vs reiser4 and effects of fragmentation.

[Hans Reiser <reiser@namesys.com>]

Markus Törnqvist wrote:

>On Thu, Sep 16, 2004 at 07:38:36PM +0400, Alex Zarochentsev wrote:
>
>  
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>>We are not going to add more intelligence to the in-kernel repacker module but
>>design an interface between repacker and user-space programs and implement
>>reisizing alg. in user-space. 
>>    
>>
>
>This sounds a bit fishy; is it about having two repackers then?
>One in kernelspace and one in userspace?
>Will the kernelspace one be obsoleted?
>  
>
The kernel will perform transactions requested by user space.  These 
transactions will be composed by the user space program.

We will start with the simple algorithm we currently use, and then Zam 
and I will go read Knuth and Woods and the web to seriously research 
sorting algorithms which we haven't done yet. 

>>>>unmergable units shouldn't be problem for the reiser4 kernel code.
>>>>        
>>>>
>>>What are their significance; what do they mean?
>>>      
>>>
>>two extent units (start1, len1), (start2, len2) can be merged into one (start1,
>>len1 + len2) because start1 + len1 == start2.  I think no reiser4 kernel code
>>depends on that mergable extents do not exist.
>>    
>>
>
>Unmergable units are then (start1 + len1) != start2 because the repacker
>messed this up? 
>
>The kernel finds the extent units from their "old places" without optimizing
>them to one unit?
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>