[THIN] Re: Citrix Performance - Processor Scheduling and Memory Usage

  • From: "Andrew Wood" <andrew.wood@xxxxxxxxxxxxxxxx>
  • To: <thin@xxxxxxxxxxxxx>
  • Date: Thu, 21 Jul 2011 10:38:15 +0100

The thing to remember about optimal Citrix performance is that - there is no
one universal setting that will work for all environments every time: each
environment can be different - test it first. And, think through
effort-to-performance:  you could spend weeks messing around with
performance stats and end up getting an extra 2% performance - but really,
would your punters notice? Still, gave me a chance to dust off this document
from IBM on Windows 2003 tuning.


Anyhoo - there's a useful document from Citrix:


Top 10 Items Found by Citrix Consulting on Assessments


Which in turn leads you to the Citrix Advanced Concepts guide(s):


In terms of that specific memory optimisation - I've always gone with
setting it to system cache (not programs) and "background tasks" (not
programs)* - which goes against some the generally excellent advice outlined




The reg entry is LargeSystemCache


HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory
Management LargeSystemCache = REG_DWORD: 1


This setting allocates additional memory to the File System Cache. From
Windows Server 2003, Microsoft moved the registry from Paged Pool RAM and
into the File System Cache. Running out of File System Cache will prevent
users' ntuser.dat files (profiles) from loading. 




With the suggestion of having a looksee at



Processor Usage

To be fair, if it was just terminal services/rds on its own, the better
setting would be "programs" - this is because this it sets the timeslice
quantum to be nice and short - everyone getting a better crack of the whip.
But in XenApp you can turn on funky CPU utilization management  (other 3rd
party CPU management tools are available) in which case you should set it to
background services (otherwise you either get errors or the CPU utilization
management doesn't work as effectively) 


And here's a nice article all about that -






From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf
Of Angela Smith
Sent: 21 July 2011 01:23
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: Citrix Performance - Processor Scheduling and Memory


I was hoping there would be a clear answer to this..  I remember years ago
reading about it and everyone had it set differently..  Hopefully someone
can provide "best practice" advice on what it should be set to for optimal
Citrix performance.


From: rich@xxxxxxxxxxxxxxxxxx
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: Citrix Performance - Processor Scheduling and Memory
Date: Wed, 20 Jul 2011 16:40:58 -0400

Funny, I just a Citrix engineer tell me to set it to System Cache!


From: Mark.Landin@xxxxxxxxxxxxxxxx
To: thin@xxxxxxxxxxxxx
Date: Wed, 20 Jul 2011 15:38:25 -0500
Subject: [THIN] Re: Citrix Performance - Processor Scheduling and Memory

Memory Usage should be set to Applications (or whatever is NOT "System



From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf
Of Angela Smith
Sent: Wednesday, July 20, 2011 5:21 AM
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Citrix Performance - Processor Scheduling and Memory Usage



What is the correct setting for Citrix Performance.  A default Windows 2003
R2 Server install defaults to: 

Processor Scheduling 

Memory Usage 
System Cache

Is this OK or should I change it?




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