Command to check memory used or consumed by OS kernel


 
Thread Tools Search this Thread
Top Forums UNIX for Advanced & Expert Users Command to check memory used or consumed by OS kernel
# 1  
Old 07-04-2017
Command to check memory used or consumed by OS kernel

I am trying to check how much memory is consumed by OS Kernel using below command, Is this the correct command that I'm using

Code:
grep Slab /proc/meminfo

Output : Slab: 3106824 kB
IF I convert KB to GB, It means 2.9 GB of RAM is consumed


Below details for reference
Code:
  uname -a (6.8 santiago)
2.6.32-696.1.1.el6.x86_64 #1 SMP Tue Mar 21 12:19:18 EDT 2017 x86_64 x86_64 x86_64 GNU/Linux


Last edited by vbe; 07-04-2017 at 04:02 AM..
# 2  
Old 07-04-2017
Quote:
Originally Posted by sam@sam
I am trying to check how much memory is consumed by OS Kernel using below command, Is this the correct command that I'm using

Code:
grep Slab /proc/meminfo

According to this document this is not (quite) the correct command. To quote the linked explanation:

Quote:
Slab - The total amount of memory, in kilobytes, used by the kernel to cache data structures for its own use.
Note that "kernel" isn't a monolithic process. In fact the "kernel" consists of several processes, depending on how the system is configured, what it is doing, how much memory it has installed and perhaps a few other things. So it is difficult to point to one certain place and declare it to be the answer. The value you found is arguably part of the answer but if it is depends on what exactly the question is.

Can you tell us what exactly you want, so that maybe we can find some better solution?

I hope this helps.

bakunin
# 3  
Old 07-04-2017
Hi Bakunin,

I have many application running on LINUX box, RAM allocated on this box is 15GB
I want to know how much memory is consumed by Applications and OS

Code:
              total        used       free     shared    buffers     cached
Mem:            15G         14G       627M       932K       1.4G       916M
-/+ buffers/cache:        12G       2.9G
Swap:           9G          898M       9.1G


From application level only 12 GB RAM is allocated out of it only 8 GB RAM is consumed currently

But I'm unable to figure out how much RAM is consumed by OS on an average?
If I have a margin of how much RAM is consumed to OS then in future if I need to add any new software/app I can recommend for extra RAM in LINUX BOX, hope you understand

Moderator's Comments:
Mod Comment edit by bakunin: please use CODE-tags for data too, thank you.

Last edited by bakunin; 07-04-2017 at 08:19 AM..
# 4  
Old 07-04-2017
Quote:
Originally Posted by sam@sam
I have many application running on LINUX box, RAM allocated on this box is 15GB
I want to know how much memory is consumed by Applications and OS
OK, now we're talking.

From the output you provided i read it like this:

You have 15G or RAM, of which ~14G are in (various) use, ~650M are unused. Of the 14G of used RAM ~2.5G are used for buffers and cache, leaving ~11.5G for kernel and applications. When you say ~8G are used for applications that would leave ~3.5G to the kernel. I don't know the Linux kernel well enough to say if the file cache is included in this figure or not.

You can check the memory footprint of running processes by using the -o vsz parameter to the ps-command (SystemV-version). i.e.

Code:
ps -Ao vsz,args

will show all processes with the allocated memory (virtual+physical, in KB) and the command lines to invoke them. You need to add the shared memory segments which you can find out about with the ipcs command:

Code:
ipcs -m

to get the complete memory used by applications.

Refer to the man pages of the named commands for details.

I hope this helps.

bakunin
This User Gave Thanks to bakunin For This Post:
# 5  
Old 07-04-2017
Thanks for the response but The commands which you have provided does meet my need.

My requirement was to check only RAM (not virtual memory) consumed by OS kernel or allocated to OS kernel

Is this possible by using below command
grep Slab /proc/meminfo
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. AIX

Process, PID and total memory consumed on AIX.

Hi, Below is the code snippet I use on Linux (Centos) to retrieve the Process Name, PID and memory consumed on Linux (Centos) host:- top -b -n 1 | awk -v date="$tdydate" -v ip="$ip" 'NR>7 {print date","ip","$12,","$1,","$10}' Any idea how the same can be retrieved on an AIX host? This... (1 Reply)
Discussion started by: Vipin Batra
1 Replies

2. Solaris

Logging the memory consumed by a process with c/C++ without using proc

I need to log the size of physical/virtual memory consumed by any given given process using c/c++ code running on solaris and aix without using the proc filesystem. Please advise. (1 Reply)
Discussion started by: Manisha Paul
1 Replies

3. Red Hat

PAE kernel memory limit

What is the limit of LowMem and HighMem in PAE enable kernel. (2 Replies)
Discussion started by: hiten.r.chauhan
2 Replies

4. Shell Programming and Scripting

How can I obtain the consumed memory of a process?

Hi!!! how can I obtain the consumed memory of a process? nowadays i'm using ps -efo pid, pmem, comm,args .... but the information is in percentage, is that correct? so, i want to know how can obtain the consumed memory of a process in mb? thanks in advance! Richard (3 Replies)
Discussion started by: rcrutz_18
3 Replies

5. HP-UX

Order process by consumed memory

Hi! I am new to HP-UX. :o By using the command glance, I found the user memory usage was very high. I would like to know is there any command can show the process which consume most available memory ? (Just like the command top, but order by memory, not CPU) (1 Reply)
Discussion started by: alfredo
1 Replies

6. Solaris

Command to check memory size

Hi, I am looking for acoomand on HP where by i can see the CPU increasing for a given process ... I know i can see this from top/prstat .. But it will give for all the processes - I want something like say ps where i can call it from a shell script a few times and check if it is has increased... (0 Replies)
Discussion started by: nano2
0 Replies

7. UNIX for Advanced & Expert Users

the amount of memory consumed per user

Hi, under UNIX AIX how determine the amount of memory consumed per user ? Many thanks before. (1 Reply)
Discussion started by: big123456
1 Replies

8. AIX

Kernel use of real memory

Hello AIX gurues... In order to present the statistics of real memory usage I need to know how much real memory is used by the AIX 5L kernel. No the exact figures of course but some close to the reality. The AIX is running in a 7GB real machine, it has a HACMP configuration and my concern is... (1 Reply)
Discussion started by: daniels
1 Replies

9. HP-UX

kernel, memory and patches information

I kind of forget easily. Is anyone remember the command to find kernel, memory and patches information of HPUX 11.0 machine? Thank you! (0 Replies)
Discussion started by: Teh Tiack Ein
0 Replies

10. Solaris

1. To know the Memory consumed by a process at a time

hello I am new to the UNIX I want to know what command is used 1.To know the Memory consumed by a process at a time . 2.To know the How many CPU's in a server. 3.To know the RAM size. 4.To know the Hard Disk size. (3 Replies)
Discussion started by: maheshkoushik
3 Replies
Login or Register to Ask a Question