Performance numbers?

[Eric Anderson]

On Feb 2, 2009, at 3:16 AM, Ivan Voras wrote:

> 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.


Ok, I tried gzero, and now the numbers are *much* different.  I'm  
getting roughly 60,000 ops/s now single threaded, or about 140,000 ops/ 
s using 4 threads.  Much better! :)  I could not for the life of me  
remember geom_zero, so thanks for the reminder.


>
>
>> 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.
>



I think I'll skip that now that I have gzero working giving me more  
realistic numbers.

Eric