Dynamips/GNS3, .net files, and Cisco networking labs.
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mellowd
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Re: Drastically decreasing CPU load in Dynamips

Fri Sep 16, 2011 8:47 am

I use it in my current CCIE labs which sometimes run for 8 hours straight. Not once had I ever had an issue with it.

Sepiraph
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Re: Drastically decreasing CPU load in Dynamips

Fri Sep 23, 2011 10:20 pm

wirerat wrote:BGP lab on Linux went down from 75% to about 37%. I wonder why this has not been widely known until now.


It was known at least from 2007. Pretty sure the creator(s) of dynamics would be aware of it as well.

http://7200emu.hacki.at/viewtopic.php?t=4146

http://7200emu.hacki.at/viewtopic.php?p ... 3279f5a994
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williamtyrell78
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Re: Drastically decreasing CPU load in Dynamips

Mon Jun 03, 2013 3:12 pm

Pick a Asterix'd IdlePC value for your platform

Then imput this command in console:
Code: Select all
idlepc idlemax /all 10


This dropped me from 100% to 11% with everything running (including broswer/exchange/etc)

I am emulation over 10 7200's and only using 10% average....
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Ironman401
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Re: Drastically decreasing CPU load in Dynamips

Fri Nov 15, 2013 4:06 pm

Huh? I opened my .net file with notepad and searched for idlemax and couldn't find it anywhere. . . . .
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timhalo
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Re: Drastically decreasing CPU load in Dynamips

Sat Nov 16, 2013 12:20 am

You can add it. It goes in the router model section..for example...

Code: Select all
[[3725]]
 image = ...
 ram = 128
 idlepc = 0x60bec530
 idlemax = 200
 ghostios = false
 mmap = false
 sparsemem = false

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Ironman401
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Re: Drastically decreasing CPU load in Dynamips

Mon Nov 18, 2013 8:56 am

I will have to give this a shot, thanks!
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Syncursion
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Re: Drastically decreasing CPU load in Dynamips

Thu May 15, 2014 6:17 pm

I tried this tonight inside my network. I'm running at least 30 routers, with an ASA, some VMs, etc etc. All 8 cores are hovering around 60%. I applied an idle max of 100, and this brought my router's performance down a lot. My cores were running at only about 30%, but the devices were obviously suffering. When consoled, I'd have to wait ~20 seconds to get a response at first. EIGRP started periodically dropping neighborships as well. This setting may not be very scalable. I tried increasing the idle max value a little, but I kept having odd issues.

However, I decided to try a balanced solution to see if I could lower my CPU usage a little. Using cpulimit (this was already being used for the ASA), I wrote a bash script to grab the PID of all running dynamips processes. Then, I used cpulimit to set the limit of these PIDs to 30%. I chose 30% from looking at what dynamips was already consuming, and 30% seems like a nice middle ground that would lower them a bit without crippling them. I seem to have chosen wisely, because my CPUs dropped to about 45% on all cores (down from over 60%), and I ran constant pings to many devices throughout the network, without dropping a single packet.

In short, this works but be careful because it may affect your devices performance.

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