cpu usage per process? - linux

Question

How can I grab the percentage of cpu usage on a per process basis? So, for example, I'd like to run my program prog and get the cpu usage it incurred in, for example:
prog name cpu0 cpu1 cpu2 cpu3 total
prog 15 20 45 47 127%
Is there any tool for this?
Thanks.

Answer 1

I think that you can make use of the information in /proc/[pid]/stat and /proc/stat to estimate this.
Check out the great answers to How to calculate the CPU usage of a process by PID in Linux from C? which explain how to calculate CPU usage % for a single processor.
The 6th from last number you get from /proc/[pid]/stat is "processor %d, CPU number last executed on" (on Ubuntu 12.04 at least).
To extend to multiple processors, you could sample the CPU usage over a period and (very roughly!) estimate the proportion of time on each processor. Then use these proportions to split the CPU usage between the processors. Based on the info in /proc/stat you can also sample the total time for each processor and then you have all the variables you need!
See http://linux.die.net/man/5/proc for more info about proc.

Answer 2

For firefox:
while [ 1 ]; do ps --no-heading -C firefox -L -o command,psr,pcpu|sort -k 2 -n; echo; sleep 1; done
You'd have to sum the third column (which I see no ridiculously easy way to do) because it's actually showing you every thread. First column is name, second processor, third, %cpu.

Answer 3

linux process explorer project provides this functionality, you can see a graph for the CPU/Memory/IO for each process in the properties dialog.

Answer 4

Here is a simple python i've made:
import re,time,sys
cpuNum=0
if len(sys.argv)==1:
print "use pidcpu <pid1,pid2,..,pidn>"
sys.exit(0)
pids=sys.argv.pop()
def getCpuTot():
global cpuNum
f=open("/proc/stat","r")
ln=f.read()
f.close()
#cpu 858286704 148088 54216880 117129864 2806189 5046 16997674 0 0 0
r=re.findall("cpu[\d\s]{1}\s+(\d+)\s(\d+)\s(\d+)\s(\d+)\s.*?",ln,re.DOTALL)
cpuNum=len(r)-1
return int(r[0][0])+int(r[0][1])+int(r[0][2])+int(r[0][3])
def getPidCPU(pid):
f=open("/proc/"+ str(pid) +"/stat","r")
ln=f.readline()
f.close()
a=ln.split(" ")
return int(a[13])+int(a[14])
cpu1=getCpuTot()
cpupid1=[]
for pid in pids.split(","):
cpupid1.append(getPidCPU(pid))
time.sleep(1)
cpu2=getCpuTot()
cpupid2=[]
for pid in pids.split(","):
cpupid2.append(getPidCPU(pid))
i=0
for pid in pids.split(","):
perc=int(cpuNum*(cpupid2[i]-cpupid1[i])*100/float(cpu2-cpu1))
i+=1
print pid,perc