Re: Performance Adjustments: Silly Frames and poll() timeout

Mark Richardson wrote most of that.

I suspect the optimization you are doing is optimising for a
single connection.  I am wondering what the behavior on the
"server" side will be when it accepts more than 1 connection.

I think, if I remember correctly, Mark was somewhat concerned 
with portability and so made some least common denominator
trype choices in the poll code.  I can well believe that tuning
may be needed.  I think the timeouts as set are pessimistic,
and probably should be set based on the actual number of session 
rather than the max.

-bill


On Wed, Apr 07, 2004 at 05:30:18PM -0400, David C Niemi wrote:
> On Tue, 6 Apr 2004, Lei Zhang wrote:
> > So you have 768 /3 = 256 sessions in a single process?  Can you make 
> > your application host smaller number of sessions?  I played a little 
> > with the timeout value of poll() a little a while ago, my purpose then 
> > was to see if that helps reduce the CPU usage of my beepcore-c based 
> > application - and noticed the problem you described in this thread.
> 
> I have done some more real testing, and find that subtle changes in the 
> vicinity of this poll() call have a rather large impact on performance 
> (latency in particular).  It looks like for my current setup about a 10 
> msec timeout to poll() is optimal; reducing it further does not help and 
> seems to slightly increase CPU consumption.  But going up to even 20 msec 
> makes things noticeably slower.
> 
> Who wrote this code?  It is obviously rather intricate and in many ways 
> hard to improve upon, but it seems to me some sort of change may be called 
> for (if nothing else, to always set the timeout to 1/HZ).
> 
> -------------------------------------------------------
> -- David C. Niemi           Adeptech Systems, Inc.   --
> -- Reston, Virginia, USA    http://www.adeptech.com/ --
> -------------------------------------------------------
> 


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