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From:	"Gary Rowe" <gary AT rowandelle DOT com>
To:	cygwin AT cygwin DOT com
Date:	Mon, 28 Jan 2008 21:51:51 -0000
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Subject:	Erratic performance with Cygserver
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Hi,

I am helping someone with a system that makes use of the msgsnd and 
msgrcv calls to xfer messages between components using Queues and 
Fifos:

I/O Listener -> Router -> Process Module
I/O Sender <- Router <- Process Module  


The problem is the performance - on a medium-size Unix system (e.g. 4 
CPU HP system) they get 600 messages through the system per second, 
when the Process Module is handling database enquiries.

On a 4 CPU windows system with Cygserver (4 x Intel Xeon 3.2GHz, 
3.5Gb RAM) they are struggling to get even 4-5 messages through the 
system in a second, even with a *dummy* Process Module which does no 
database access, only returning a 'success' message!

We have tested with Cygwin 1.5.24-2 and 1.5.25-5

We have turned off Hyperthreading and disabled the anti-virus from 
scanning the application and cygwin folder structures on the servers, and 
amended cygserver.conf, but are hitting this wall in the performance.

(response msgs can be up to 4096 bytes, I set 

# kern.ipc.msgssz: Size of segment in bytes.  Must be a power of 2 value.
# Default: 8, Min: 8, Max: 1024
kern.ipc.msgssz 256

# kern.ipc.msgmnb: Maximum no. of bytes in a single message queue.
# Default: 2048, Min: 1, Max: 65535
kern.ipc.msgmnb 65535)

I cannot see how to enable any kind of performance monitoring in 
Cygserver, and through the debug in their system I see that the responses 
from Cygserver can have significant delays at times, but I can't see any 
pattern to the delays.

Please can anyone suggest what to look into to track down where the 
problem may be, and what diagnostics / debug could help me?  I cannot 
find any discussions on problems with Cygserver performance on the net, 
so I have to assume it is a problem with their setup ... but it's happening on 
their two test servers, and also on site!

Gary
___________________________________________________
Gary Rowe, Dublin, Ireland	
www.rowandelle.com



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