awk's sum not working?

grob115 · 04-29-2010, 11:45 AM

Hello,

Trying to get a total of the memory consumption for the httpd process. The 10th column is displaying the % used. Just wondering how the summed value is able to get over 100%?

[root@vps htdocs]# /usr/bin/top -n 1 -b | grep httpd | awk '{SUM += $10} END {print SUM}' 151.9
[root@vps htdocs]# /usr/bin/top -n 1 -b | grep httpd | awk '{SUM += $10} END {print SUM}'
148.1
[root@vps htdocs]# /usr/bin/top -n 1 -b | grep httpd | awk '{SUM += $10} END {print SUM}'
104.6
[root@vps htdocs]# /usr/bin/top -n 1 -b | grep httpd | awk '{SUM += $10} END {print SUM}'
96.8

pixellany · 04-29-2010, 11:49 AM

I don't have httpd on my system, so I did this:

Code:

root@mystical mherring]# /usr/bin/top -n 1 -b | grep udevd
 1105 root      16  -4  6500 1160  412 S    0  0.0   0:00.04 udevd                                                                                            
16299 root      18  -2  6216  896  432 S    0  0.0   0:00.00 udevd                                                                                            
16300 root      18  -2  6496 1108  364 S    0  0.0   0:00.00 udevd                                                                                            
[root@mystical mherring]#

How is your AWK syntax supposed to operate on this output?

EDIT: OK, I see that you are incrementing SUB with the value of field $10. I wonder if it adds several instances? Try watching top to see what the values are on each refresh.

grob115 · 04-29-2010, 11:55 AM

Mine is exactly the same as yours. It's supposed to add the column before the one that shows the up time. Yours is showing 0.0 for all of them so these processes that you used are very small in memory usage.

Sample of my top output. Trying to add the %MEM column with the awk.

top - 10:30:04 up 652 days, 17:03, 2 users, load average: 50.00, 20.17, 8.26
Tasks: 91 total, 58 running, 29 sleeping, 0 stopped, 4 zombie
Cpu(s): 48.3% us, 6.6% sy, 0.0% ni, 41.8% id, 3.3% wa, 0.0% hi, 0.0% si
Mem: 262144k total, 256860k used, 5284k free, 0k buffers
Swap: 0k total, 0k used, 0k free, 0k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
5435 apache 16 0 39132 14m 3744 S 1.9 5.8 0:00.36 httpd
5532 apache 16 0 39460 14m 4044 R 1.9 5.8 0:02.08 httpd
5593 apache 16 0 38412 14m 3784 R 1.9 5.5 0:00.69 httpd

pixellany · 04-29-2010, 12:03 PM

I tried "top" and saw that X was averaging about 15% cpu usage. I then did "top|grep X" and X was averaging 2% cpu.

Conclusion: I'm not sure if I would trust top piped into grep. More research needed.

going back to the original problem: What is the point of summing the CPU usage values?

Tinkster · 04-29-2010, 12:44 PM

Just for a sanity check:

Code:

top -b -n 1| awk '/httpd/{print $10": "$0;sum+=$10}END{print sum}'

Seems quite right on my machine - changes if I put a bit of load on
apache, e.g., fire up some PHP based site(s).

Cheers,
Tink