exclude single core from quad core cpu for gimps

Basically what I am trying to do is to use three out of four cores for mprime on linux64. I want the fourth core to be available for the system at all times to have better desktop performance. How can this be done?
I am running mprime259-linux64 on Intel(R) Core(TM)2 Quad CPU Q9550 @ 2.83GHz and all threads have nice value 19.

[Mini-Geek]

Under Test > Worker Windows you can choose how many worker windows to run. I believe that with mprime you need to run ./mprime -m to bring up the menu.

You generally shouldn't be noticing a slowdown when running mprime at the lowest priority (like you are). Are one or more of the workers currently running P-1 stage 2? If so, you might be noticing issues related to memory usage and paging. You can set the amount of memory that mprime can use in Options > CPU to prevent this.
It might be possible that memory/cache bandwidth could be causing the issue, in which case I'd suggest changing one or two of the cores to TFing, at least temporarily to see if that fixes it. (if you change two to TFing, don't make them cores 1 and 2 or 3 and 4, break it up a bit like 1 and 3 so that it will be in more separate areas physically)

[pegaso56]

Hi, I am running one P-1 and three LMH in a Phenom II, using 2600 Mb of memory and did not find any problem for mprime 25.9, desktop runs smoothly and Xorg was reniced from 0 to 10 also without not aprecciable slowdown.
Regards, Carlos

[joblack]

Originally Posted by pegaso56

Hi, I am running one P-1 and three LMH in a Phenom II, using 2600 Mb of memory and did not find any problem for mprime 25.9, desktop runs smoothly and Xorg was reniced from 0 to 10 also without not aprecciable slowdown.
Regards, Carlos

It depends - it can slow down a little bit, especially because the Qxxxx Quads are two - double cores - and competing for the memory access. Additionally there could be a problem with your memory (virtual memory swapping because you don't have enough memory -> to a slower harddisk, ...)

That might be different for the Phenom and Core i7 (because they are 'real quad cores' and have a better memory management).

Alternative you can use two worker threads with two cpu threads (1 + 2 for one and 3 + 4 for another) so you have an optimized memory allocation.

That works more fluently in my case and you still have a very well desktop performance. Btw. if you compile your kernel for fast desktop latency it should be no problem whatever configuration you use ...

Originally Posted by joblack

Alternative you can use two worker threads with two cpu threads (1 + 2 for one and 3 + 4 for another) so you have an optimized memory allocation.

How would I configure that?




For the moment I changed my start script to forcibly assign only three cores to mprime. For all of you wondering how I managed this, take a look at lines 12 ~ 18. The disadvantage is that still 4 threads are started, whereas I'd rather run only three, but now they run on only three cores, which means 2 threads are running at 50% cpu. At least my system (and especially disk i/o) is a *lot* better than before.
Using the setup below, it is rather easy to add or remove cores from mprime :)

     1  #! /bin/sh                                                                                                                                         
     2  ### BEGIN INIT INFO                                                                                                                                
     3  # Provides:                                                                                                                                        
     4  # Required-Start:                                                                                                                                  
     5  # Required-Stop:                                                                                                                                   
     6  # Default-Start:                                                                                                                                   
     7  # Default-Stop:                                                                                                                                    
     8  # Short-Description: Start or stop gimps mprime                                                                                                    
     9  # Description:                                                                                                                                     
    10  ### END INIT INFO                                                                                                                                  
    11                                                                                                                                                     
    12  test -d /dev/cgroup || mkdir /dev/cgroup                                                                                                           
    13  # mount -t cgroup cpuset -ocpuset /dev/cgroup                                                                                                      
    14  mount -t cgroup cgroup /dev/cgroup                                                                                                                 
    15  test -d /dev/cgroup/gimps || mkdir /dev/cgroup/gimps                                                                                               
    16  echo 1-3 > /dev/cgroup/gimps/cpuset.cpus                                                                                                           
    17  echo 0   > /dev/cgroup/gimps/cpuset.mems                                                                                                           
    18  echo 0   > /dev/cgroup/gimps/tasks                                                                                                                 
    19                                                                                                                                                     
    20                                                                                                                                                     
    21                                                                                                                                                     
    22  PATH=/sbin:/bin  # No remote fs at start                                                                                                           
    23  DAEMON=/opt/gimps/mprime                                                                                                                           
    24  [ -x "$DAEMON" ] || exit 0                                                                                                                         
    25  NAME=gimps                                                                                                                                         
    26  DESC="GIMPS mprime"                                                                                                                                
    27                                                                                                                                                     
    28  GIMPS_DIR=/opt/gimps                                                                                                                               
    29  USER=gimps                                                                                                                                         
    30  GROUP=gimps                                                                                                                                        
    31  GIMPS_OPTS=                                                                                                                                        
    32                                                                                                                                                     
    33  # BOOTLOGD_OPTS="-r -c"                                                                                                                            
    34  [ -r /etc/default/gimps ] && . /etc/default/gimps                                                                                                  
    35  . /lib/init/vars.sh                                                                                                                                
    36                                                                                                                                                     
    37  . /lib/lsb/init-functions                                                                                                                          
    38                                                                                                                                                     
    39  SCRIPTNAME=${0##*/}                                                                                                                                
    40  SCRIPTNAME=${SCRIPTNAME#[SK]??}                                                                                                                    
    41  ACTION="$1"                                                                                                                                        
    42                                                                                                                                                     
    43  case "$ACTION" in                                                                                                                                  
    44    start)                                                                                                                                           
    45          # PATH is set above                                                                                                                        
    46          log_daemon_msg "Starting $DESC" "$NAME"
    47                  umask 027
    48                  start-stop-daemon --start --quiet --background \
    49                  --chdir ${GIMPS_DIR} --chuid ${USER}:${GROUP} \
    50                  --nicelevel 19 --exec $DAEMON --
    51                  # -- $GIMPS_OPTS
    52                  ES=$?
    53          log_end_msg $ES
    54          ;;
    55    stop)
    56          PATH=/bin:/sbin:/usr/bin:/usr/sbin
    57          log_daemon_msg "Stopping $DESC" "$NAME"
    58          start-stop-daemon --oknodo --stop --quiet --exec $DAEMON
    59          ES=$?
    60          sleep 1
    61          log_end_msg $ES
    62          ;;
    63    restart|force-reload)
    64          /etc/init.d/bootlogd stop
    65          /etc/init.d/bootlogd start
    66          ;;
    67    status)
    68          status_of_proc "$DAEMON" "$NAME" && exit 0 || exit $?
    69          ;;
    70    *)
    71          echo "Usage: $SCRIPTNAME {start|stop|restart|force-reload|status}" >&2
    72          exit 3
    73          ;;
    74  esac
    75
    76  :

[Mini-Geek]

Originally Posted by Unregistered

How would I configure that?

(hopefully there's no difference between the mprime and Prime95 menus, if there is just try to find the equivalent options or ask for someone experienced with mprime)
1. close mprime
2. run mprime -m to open the menu
3. go to Test > Worker Windows
4. set Number of worker windows to run to 2
5. choose to modify the settings for All workers (alternately, do it one worker at a time)
6. set CPUs to use to 2 (this is per-worker, so 2x2)
7. exit mprime
8. your worktodo.txt file will look something like this:

[Worker #1]
Test=0123456789ABCD...,50000003,69,1

[Worker #2]
Test=123956789ABCD...,50000009,69,1

[Worker #3]
Test=2687456789ABCD...,50000011,69,1

[Worker #4]
Test=3984256789ABCD...,50000017,69,1

You need to make it so there's just two sections, but you don't want to lose your assignments, so merge #3's and #4's lines into the #1 and #2 sections, then delete the #3 and #4 headers, like this, and save the file: (do not use these exact lines, these are just examples to show you what you'll be doing)

[Worker #1]
Test=0123456789ABCD...,50000003,69,1
Test=2687456789ABCD...,50000011,69,1

[Worker #2]
Test=123956789ABCD...,50000009,69,1
Test=3984256789ABCD...,50000017,69,1

9. start mprime. It will now have two workers each using two threads, and default to cores 1 and 2 for the 1st worker and cores 3 and 4 for the 2nd worker.

[jrk]

Originally Posted by jippie

I want the fourth core to be available for the system at all times to have better desktop performance.

If you don't mind rebuilding the kernel instead,

Try with Con Kolivas's BFS patch and then start mprime with schedtool to set it as SCHED_IDLEPRIO ("schedtool -D -e ./mprime").

Running Kubuntu 9.10, it appears that I do not have to rebuild the kernel, just had to install the schedtool. Running with:

$ schedtool 23633
PID 23633: PRIO   0, POLICY D: SCHED_IDLEPRIO, NICE  19, AFFINITY 0xf

I'll be trying this for a while instead of my taskset trickery. Thnx!

Originally Posted by jrk

If you don't mind rebuilding the kernel instead,

Try with Con Kolivas's BFS patch and then start mprime with schedtool to set it as SCHED_IDLEPRIO ("schedtool -D -e ./mprime").