Performance numbers?

[Eric Anderson]

On Jan 30, 2009, at 2:50 PM, Ivan Voras wrote:

> Eric Anderson wrote:
>> Hi GEOMers!
>>
>> Does anyone have any benchmarks or numbers relating to GEOM  
>> performance?
>>
>> I tried doing some on my own, but I didn't get very satisfactory
>> results, so I'm curious what others have seen or used.
>>
>> My hardware is a Core 2 Quad, with 4GB of ram.
>>
>> First, I made an mdconfig'ed malloc backed 'disk' of 1.5GB.  Then, I
>> tried running such tools as rawio, and diskinfo.  rawio fails with
>> input/output errors, and diskinfo wants a larger device to give the  
>> full
>> stats.  I ended up using purely dd since that worked.  Interestingly
>> enough, dd'ing to the malloc device results in about 1000  
>> operations per
>> second, regardless of a blocksize of 512bytes or 1MB.
>
> It's a good idea for testing.
>
> 1000 ops/s looks suspiciously like HZ, though I don't know why HZ  
> would
> influence GEOM (AFAIK context switches between threads, including GEOM
> threads do not depend on it) - can you try ruling out HZ?
>


Is there a way to pump the data through the GEOM layers without doing  
a mdconfig'd disk?

Also, are you thinking setting the hz to some other setting, and  
rerunning?  What setting were you thinking?  I can easily try anything.

Thanks!
Eric