Re: [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:  [EMAIL PROTECTED]
University of Missouri - Rolla         Phone: (573) 341-4841
Computing Services                       Fax: (573) 341-4216
 

-----Original Message-----
From: Nathan Ward [mailto:[EMAIL PROTECTED] 
Sent: Thursday, February 27, 2003 1:52 PM
To: [EMAIL PROTECTED]
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

[EMAIL PROTECTED] 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.
[EMAIL PROTECTED]
(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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