cpus for one process

danfou · 05-15-2007, 01:22 PM

How to limit the number of cpus that my process can use?

I look into taskset, but still have no idea?

Can someone give some detailed help, say an example command?

Thanks.

osor · 05-15-2007, 01:28 PM

I might use cpusets (I presume you’re using linux).

Marsolin · 05-15-2007, 01:44 PM

You could try cpulimit.

osor · 05-15-2007, 02:55 PM

Btw, what exactly did you not like about taskset? Let’s say I have four cpus. If I give each cpu a binary mask, I get something like this (just for fun, I start counting from cpu1, even though normally counting starts at cpu0):

Code:

CPU#  MASK  DECIMAL
cpu1  0001     1
cpu2  0010     2
cpu3  0100     4
cpu4  1000     8

What if I want a process to have affinity only for cpu1 and cpu4? I would OR the masks together for their combined mask:

Code:

cpu1 | cpu4 =
0001 | 1000 = 1001
            = 9

So let’s say this process whose affinity I’m setting has pid 1234. I would do something like this to limit its affinity to cpu1 and cpu4:

Code:

# taskset -p 9 1234

(NOTE: it is somewhat strange that the PID does not immediately follow the “-p” flag.)

osor · 05-15-2007, 03:06 PM

Quote:

Originally Posted by Marsolin

You could try cpulimit.

cpulimit (AFAICT) will limit the “percentage of cpu power” a process is able to use. This does not necessarily mean the given process will be confined to one cpu (though it should most of the time).

killerforce · 06-21-2007, 10:37 AM

hi OSOR

Code:

Btw, what exactly did you not like about taskset? Let’s say I have four cpus. If I give each cpu a binary mask, I get something like this (just for fun, I start counting from cpu1, even though normally counting starts at cpu0):
Code:

CPU# MASK DECIMAL 
cpu1 0001 1 
cpu2 0010 2 
cpu3 0100 4 
cpu4 1000 8

What if I want a process to have affinity only for cpu1 and cpu4? I would OR the masks together for their combined mask:
Code:

cpu1 | cpu4 = 0001 | 1000 = 1001 = 9

So let’s say this process whose affinity I’m setting has pid 1234. I would do something like this to limit its affinity to cpu1 and cpu4:
Code:

# taskset -p 9 1234

Quote:

Now where do you set those binary mask to the CPUs. I'm using slackware 11 with kernel 2.6.17.13. Where would I set that ?

Quote:

And if you set cpu affinity for a process using its pid, then after reboot the pid of that process might change. So how is it going to work ? Please give me some advice.