[OpenAFS] Performance

[Nathan Ward]

I seem to remember it has something to do with loading your tokens into 
the kernel also.
Anyway, thats what I would expect is all it does, so where could these 
context switches be coming from? Is there any way to trace that somehow?

Nathan

Neulinger, Nathan wrote:

>The user space daemon in afs doesn't do much of anything. It's there
>primarily to launch kernel threads and set up the cache. 
>
>-- Nathan
>
>------------------------------------------------------------
>Nathan Neulinger                       EMail:  nneul@umr.edu
>University of Missouri - Rolla         Phone: (573) 341-4841
>Computing Services                       Fax: (573) 341-4216
>
>
>  
>
>>-----Original Message-----
>>From: Nathan Ward [mailto:nward@esphion.com] 
>>Sent: Thursday, February 27, 2003 1:52 PM
>>To: emoy@apple.com
>>Cc: Michael Robokoff; openafs
>>Subject: Re: [OpenAFS] Performance
>>
>>
>>Well I'd expect that it goes slower as your cache size is 
>>exceeded as it 
>>then needs to start getting that data to the server. Or is 
>>the cache for 
>>read operations only?
>>
>>I notice that there are around about the same number of 
>>packets/sec as 
>>context switches/sec on my client machines. I wonder if 
>>switches between 
>>userland and kernel could be to blame... ? Who sends packets 
>>in OpenAFS, 
>>the userspace daemon or the kernel?
>>
>>Nathan
>>
>>emoy@apple.com wrote:
>>
>>    
>>
>>>Could the slowness you see with your dd write test be 
>>>      
>>>
>>related to the  
>>    
>>
>>>cache exhaustion issue that I raised recently, when writing a file  
>>>larger than your cache size.  Your test writes a 1 GB file, so if 
>>>your  cache is smaller than this, you will see poor 
>>>      
>>>
>>performance once 
>>    
>>
>>>your  cache size is exceeded.
>>>
>>>      
>>>
>>--------------------------------------------------------------
>>---------- 
>>    
>>
>>>-- 
>>>Edward Moy
>>>Apple Computer, Inc.
>>>emoy@apple.com
>>>
>>>(This message is from me as a reader of this list, and not 
>>>      
>>>
>>a statement
>>    
>>
>>>from Apple.)
>>>
>>>On Thursday, February 27, 2003, at 11:15  AM, Nathan Ward wrote:
>>>
>>>      
>>>
>>>>I see pretty bad performance to tell you the truth.
>>>>I can read and write ~60mb/s directly to my raid array, but when 
>>>>using  OpenAFS (locally or remotely) to the same array, I 
>>>>        
>>>>
>>get around  
>>    
>>
>>>>6-10MB/s, I have seen up to 25MB/s over a peice of 
>>>>        
>>>>
>>1000Mbps fibre.  
>>    
>>
>>>>Client and Server are both dual P3-1ghz with 1024mb ram. I notice 
>>>>the  context switches on the server at this time jump to ~10000/s, 
>>>>and on  the client ~40000/s. I imagine this is the source of my 
>>>>slowdown, but  I havn't had a chance to look into it.
>>>>
>>>>I'd be interested if anyone else has the same level of context  
>>>>switches going on.
>>>>
>>>>This is while doing a large sequential write operation (dd  
>>>>if=/dev/zero of=/afs/alb-nz.esphion.com/public/dd.out bs=256k  
>>>>count=4096).
>>>>
>>>>Michael Robokoff wrote:
>>>>
>>>>        
>>>>
>>>>>Does anyone have any Open AFS performance information they can 
>>>>>share  with me. I plan on doing a couple benchmarks and I 
>>>>>          
>>>>>
>>would like 
>>    
>>
>>>>>to have  some idea of what to expect.
>>>>>          
>>>>>
>>>_______________________________________________
>>>OpenAFS-info mailing list
>>>OpenAFS-info@openafs.org
>>>https://lists.openafs.org/mailman/listinfo/openafs-info
>>>
>>>
>>>      
>>>
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