Linux Command to Find Processor Number for a Process

cpucpu usagelinuxprocess

Is there any command in Linux to figure out, given a process, which processor the process is running? I am interested in figuring out the CPU busy and CPU idle time of that processor.

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You can use the ps command to query and display the active processor. For example, you might run:

$ ps -aF
UID        PID  PPID  C    SZ   RSS PSR STIME TTY          TIME CMD
root         1     0  0  5971  1764   1 Sep15 ?        00:00:01 /sbin/init
ubuntu   28903  2975  0  3826  1208   0 09:36 pts/0    00:00:00 ps -aF

The PSR column shows that init is running on processor 1 and ps is running on processor 0. See the manpage for ps(1) for more details on how to customize the fields that are displayed.

You can configure a graphical tool like htop to display the current active processor. Also, htop has a per-CPU load display graph, which may be what you're looking for. See, for example, the following screenshot from http://htop.sourceforge.net/.

htop screenshot

Finally, you can use the taskset tool to force affinity to a particular CPU.

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Linux – Determine which process belongs to which window in Linux System Monitor

Try the xprop command. After running xprop, click on whichever Window you believe is taking up the CPU to find out it's PID.

To narrow down the information it spits out, try:

xprop _NET_WM_PID

to get the PID specifically.

Linux – Which linux command to use to know how much RAM consumed by each process

ps -eo rss,pid,user,command --sort -size | \
awk '{ hr=$1/1024 ; printf("%13.2f Mb ",hr) } { for ( x=4 ; x<=NF ; x++ ) { printf("%s ",$x) } print "" }' | \
egrep -v 0.00

prints:

     6.65 Mb /usr/sbin/mysqld
     0.75 Mb rsyslogd -c4
    38.59 Mb /usr/sbin/apache2 -k start
    37.95 Mb /usr/sbin/apache2 -k start
    34.38 Mb /usr/sbin/apache2 -k start
    33.35 Mb /usr/sbin/apache2 -k start
    31.43 Mb /usr/sbin/apache2 -k start
     2.38 Mb /usr/bin/python /usr/bin/fail2ban-server -b -s /var/run/fail2ban/fail2ban.sock
     0.61 Mb /usr/sbin/nova-agent -q -p /var/run/nova-agent.pid -o /var/log/nova-agent.log -l info /usr/share/nova-agent/nova-agent.py
     3.00 Mb /usr/sbin/apache2 -k start
     1.71 Mb sshd: root@notty
     0.36 Mb sshd: root@pts/0
     1.10 Mb ps -eo rss,pid,user,command --sort -size
     1.40 Mb /usr/lib/openssh/sftp-server
     0.59 Mb /usr/sbin/ntpd -p /var/run/ntpd.pid -g -u 103:105
     0.08 Mb /usr/sbin/sshd -D
     0.21 Mb /sbin/init
     1.18 Mb -bash
     0.28 Mb cron
     0.88 Mb qmgr -l -t fifo -u

Keep in mind that free and top will show "cached" memory so you won't be able to tell how much is actually used and free. It's technically free to the system, though it might have to dump the cache to use it. I find free not so useful, and top only slightly more useful (plus top usually consumes any free RAM I have lol).

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