[OpenAFS] Re: Performance problems seem to be coming back

Dale Pontius pontius@btv.ibm.com
Mon, 12 Sep 2011 07:46:57 -0400

On 09/09/2011 04:42 PM, Andrew Deason wrote:
> On Fri, 09 Sep 2011 15:36:16 -0400
> Dale Pontius<pontius@btv.ibm.com>  wrote:
>> That's certainly better than using regular ping, since it's going to
>> go through the AFS message queues, etc.  In fact, the coworker next
>> door has been having some problems, and we tried this method in
>> another window on another client machine right as his script slowed
>> down, and saw a 20 second round trip time.
> rxdebug (in this method of operation) doesn't work just like "ping"
> does. Returning after 20 seconds doesn't mean packets take 20 seconds to
> traverse back and forth; it probably means some packets were dropped and
> we just retried. I think rxdebug waits for 1 second, and then retries
> and waits 2 seconds, then 4 seconds, etc. We probably could provide
> something closer to a normal "ping" utility.
In this case, I'm wanting something that acts more like normal AFS 
packets, and I believe that's what rxdebug is doing in this case.  Some 
people around here have been using ping as an indicator of network 
latency, and while it can be an indicator, I don't believe it's terribly 
representative of what is happening to AFS packets.  I believe the 
current rxdebug is more indicative, though I can accept evidence otherwise.


Dale Pontius
Senior Engineer
IBM Corporation
Phone: (802) 769-6850
Tie-Line: 446-6850
email: pontius@us.ibm.com

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