Friday Apr 04, 2008

Sun Ray resource management.

One of the great benefits of running Sun Rays at home is having the sessions always there. Just plug in the card and you get your session as if you were never away. However that also allows you to leave an application chewing CPU cycles when you are away. So to keep the interactive experience as good as possible I employ the same techniques described in “Using Solaris Resource Manager With Sun Ray” blueprint. For a long while I've wondered why IT don't do this. The keepers of our Sun Ray do and it works a treat. Which is a good thing when you share a Sun Ray Server with Tim.

Instead of setting the number of shares up to a specific value I use a multiplier so that those active on a Sun Ray get 10 times the number of shares that they would by default. While this works well it still leaves a significant load on the system from certain applications, specifically flash animations that are left running endlessly playing the games that were being played when the users card was removed. The fair share scheduler does it's thing to make CPU allocation fair but the memory use of those otherwise idle firefox sessions is significant.

So I've taken a leaf out of the BOFH and apply some special sanctions to those processes. Alas I may not get a job with the BOFH as my sanctions are simply to pstop(1) the copies of firefox associated with the user and DISPLAY when they detach and then prun(1) them when the user reconnects. I wondered about using memory resource caps to limit the memory but that would leave the systems rcapd(1M) battling the memory usage of the firefox processes which are not displaying anything anyway. In the unlikely event that any of the users are using their firefox sessions to simulate nuclear fission or crack SSL so would rather they kept running I'm sure they will get back to me.

So the script I have for doing this is slightly more complex than the one from the Blueprint. Since it has to err on the side of caution when stopping users firefox sessions. To do that it uses pargs(1) to make sure that the firefox sessions are really for this display. In practice I am the only person who might remote display a firefox session from here and even that is unlikely but it is the principle. The impact on the system of not trying to run all the disconnected firefox sessions is amazing.

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This is the old blog of Chris Gerhard. It has mostly moved to http://chrisgerhard.wordpress.com

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