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Old 2008-01-26, 17:37   #1
dswanson's Avatar
Aug 2002

23×52 Posts
Default Startup config for Quad Core on Linux

I just got my first Quad core system, and I'm trying to get it to run an instance of mprime v24.13.2 on each core. But it behaves like it's trying to run all instances on the same core.

Benchmark doesn't seem to be any good (it reports the essentially the same benchmark times regardless of how many instances I have going). But using a stopwatch to time the Benchmark resulted in...
Benchmark only: 0:30
Benchmark + 1 LL: 1:02
Benchmark + 2 LL: 1:35
Benchmark + 3 LL: 2:06

I also got essentially the same results looking at the per-iteration time running instances of an 896K FFT...
1 instance: 0.022
2 instances: 0.044
3 instances: 0.065
4 instances: 0.087

I'm using the "Affinity=n" option in my local.ini to assign each instance to a different core. I've also tried using "./mprime -Bn" when starting each instance, but that changes nothing.

I'm running a Q6600 with no overclock on an Asus P5N-E SLI motherboard (that was a mistake, as I just learned from another thread). I'm not sure if the operating system matters, but it's a network-boot minimal LTSP kernel (vmlinuz-2.4.22-ltsp-2).

Here's a copy of one of my four local.ini files. The other 3 are identical except for the ComputerID and the Affinity.

Any ideas?
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Old 2008-01-26, 19:31   #2
S485122's Avatar
Sep 2006
Brussels, Belgium

33318 Posts

From the README.TXT file I conclude that one sets the affinity with the -An switch, not -Bn. -Bn is an obsolete syntax from what I remember from some posts I cannot find at the moment.

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Old 2008-01-26, 21:12   #3
ckdo's Avatar
Dec 2007
Cleves, Germany

2×5×53 Posts

To S485122:

Neither -A nor -B have *anything* to do with the affinity setting.

To dswanson:

Worst news first. Last time I checked (looong ago), the default LTSP kernel wasn't SMP enabled. If that were still the case, it would perfectly explain your iteration times.

As for actually running the client, "./mprime -B4" will eventually be fine for you *if* you intend to run all instances from the same directory (which I recommend) *however* you will not get any screen output since the -d switch is ignored with -B.

I prefer to run all instances in a single terminal window so that their output is mixed and I can see quickly when one of them misbehaves. I have a shell script to start them:

kossy@leela:~/mprime$ cat ./__start
./mprime -d &
./mprime -d -A1 &
./mprime -d -A2 &
./mprime -d -A3

A Ctrl-C in that terminal window will stop all instances.

local.ini has "Affinity=0", loca0001.ini has "Affinity=1", etc.

Hope this helps.
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Old 2008-01-26, 21:52   #4
dswanson's Avatar
Aug 2002

23·52 Posts

The "looong ago" part may explain matters. The kernel I'm using is from early 2003. It's been working just fine for my farm machines, so I've never had a reason to update it. Sounds like that may be something to try.

I'll give the -An option a try too.

For me the need to see output, mixed or not, isn't a priority -- I'm running diskless and headless.
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Old 2008-01-28, 16:29   #5
garo's Avatar
Aug 2002
Termonfeckin, IE

22·691 Posts

2.4 does not support affinity setting. 2.6 does so you may wish to update to it. I learned the hard way.
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