[OpenAFS] Performance

[Nathan Ward]

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.
>>
>
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