Re: Status Update : Deployment of DOSEMU Application Server

[Shaw Tong Tan <shawtan@yahoo.com>]

Continuation of previous post.

A.  100% CPU remedy.

Original background
1.  test environment Pentium E2180/CentOS 5.2 (32-bit)/DOSEMU+FreeDOS 1.4.0 from website.
2.  I found maximum 4 instances on single host, after that random delay and hangs
3.  Std OS environment without any modification.

To arrive at a solution
1.  tried several DOS utilities, example dosidles, even citrix utility
2.  I spent weeks trying many combination.  Finally I adopted a combined recommendations from list member Joe to run BX200FIX and setting nice value.  I added a CPU control as well. Example below

EXAMPLE:  taskset -c 1 nice -n 19 dosemu

run DOSEMU with nice value of 19 on CPU Core number 1.  Dualcore CPU core is 0,1 Quad Core is 0,1,2,3

After implementation, I tested up to 6 clipper-based app instances on 1 cpu core and found response reasonable and stable, no random hangs.  Based on my assessment of the overall situation, I feel 6 session/cpu-core is the maximum I am willing to commit.  Since I have quad-core host now, I am willing to spread the load across to gain a bit of buffer zone.  Note that try not to use Core-0 for dosemu because that's the default for OS and system services.  The high cache size on Quad Core also help I think in reducing the memory contention issue.