[Spread-users] Spread segments w/o active daemons cause delays in other segments

[Dmitry Korsun]

Ryan,

    Thanks for the quick reply.  I profiled the suggested configuration 
and found no performance drop in local spread message transfer rate (the 
3rd machine does not run a spread daemon).  After a few tests I think I 
traced the delay cause down to the timeouts defined in membership.c - 
they are adjusted based on Wide_network flag.  From what I understand 
the Timeouts are increased if more than 1 segment is defined and at 
least one segment services a different subnet.  This is exactly the 
scenario found in my configuration.
    Just to confirm, I recompiled spread and hardcoded Wide_network=0.  
The delay phenomenon described below disappeared.  Is there a way to 
determine which timeout is responsible for such behavior (other than 
adjusting each one at a time and re-running the tests) ? 

    On a separate topic, I came across "Flow Control" settings for 
spread daemons.  However, the spread documentation barely mentions it 
and does not go into detail about the values - window size, and the 
values assigned to each of the daemons (that's how spmonitor configures 
the flow control parameters).

Any help would be greately appreciated,
Thanks.

-Dmitry K.

Ryan Caudy wrote:

>I can't think of anything that would cause this performance drop. 
>Just out of curiosity, can you try adding a third daemon to the first
>segment in the configuration file, removing the second segment, and
>repeating the tests with the same two daemons up and participating?
>
>Cheers,
>Ryan
>
>
>On Thu, 17 Mar 2005 23:37:39 -0500, Dmitry Korsun <dkorsu at corp.idt.net> wrote:
>  
>
>>Hi all.
>> I am relatively new to Spread and have stumbled across a problem that I
>>need help with resolving. Apparently adding a second Spread segment
>>without any spread daemons causes a big performance drop in the first
>>segment, even when clients are connecting to a member of the first
>>segment locally.
>>
>>Here are the scenarios:
>>
>>I was getting really good performance results when using a single
>>segment configuration with spread daemons runing on BOTH machines in the
>>segment:
>>#
>>Spread_Segment 172.16.202.255:4803 {
>>       DevLinuxPro     172.16.202.64
>>       StarDev1 172.16.202.77
>>}
>>#
>>Performance was tested by using spflooder utility and connecting to the
>>spread daemon LOCALLY:
>>devlinuxpro$ time spflooder -u ya -m 10000 -b 100 -s 4803 at devlinuxpro
>>flooder: connecting to 4803 at devlinuxpro.mis.idt.net
>>flooder: starting  multicast of 10000 messages, 100 bytes each.
>>flooder: completed  10000 messages of 100 bytes
>>flooder: completed multicast of 10000 messages, 100 bytes each.
>>real    0m0.559s
>>user    0m0.020s
>>sys     0m0.240s
>>
>>This yields ~20000 messages/sec
>>
>>Once a second segment was configured but no daemon started on the new
>>segment machine, performance dropped dramatically:
>>#
>>Spread_Segment 169.132.9.255:4803 {
>>       dev_1       169.132.9.113
>>}
>>#
>>Again, performance was tested LOCALLY on the machine that is part of the
>>first segment:
>>devlinuxpro$ time spflooder -u ya -m 10000 -b 100 -s
>>4803 at devlinuxpro.mis.idt.net
>>flooder: connecting to 4803 at devlinuxpro.mis.idt.net
>>flooder: starting  multicast of 10000 messages, 100 bytes each.
>>flooder: completed multicast of 10000 messages, 100 bytes each.
>>real    0m25.543s
>>user    0m0.060s
>>sys     0m0.960s
>>Now we are down to ~400 messages/sec.
>>
>>I about to test performance once a spread daemon is brought up on the
>>second segment.
>>
>>Question - why does this addition of a segment without a daemon process
>>affect performance on a entirely different segment, especially the LOCAL
>>performance.  Is there a way to configure SPREAD so that different
>>segments do not affect each other's performance ?
>>
>>Thank you in advance,
>>Dmitry Korsun
>>
>>--
>>::::::::::::...... .  .   .
>>:: Dmitry Korsun
>>:: x4095
>>:: dmitry.korsun at corp.idt.net
>>:::::::::::::::::....... .   .       .
>>
>>--
>>::::::::::::...... .  .   .
>>:: Dmitry Korsun
>>:: x4095
>>:: dmitry.korsun at corp.idt.net
>>:::::::::::::::::....... .   .       .
>>
>>_______________________________________________
>>Spread-users mailing list
>>Spread-users at lists.spread.org
>>http://lists.spread.org/mailman/listinfo/spread-users
>>
>>    
>>


-- 
::::::::::::...... .  .   .
:: Dmitry Korsun
:: x4095
:: dmitry.korsun at corp.idt.net
:::::::::::::::::....... .   .       .