Performance numbers?

[Ivan Voras]

Eric Anderson wrote:
> 
> 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?

You could use gzero, it ignores written data and produces read data with
memset.

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

Yes. Try 1500.

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