I have two questions on Linux's free command. Below, I have provided output from my home laptop (fedora 26 ) which has 16GB Physical RAM and a production server (RHEL 7.4) which has 24GB RAM.
Question1. What exactly does the buffer/cache column say in free command's output ? buffer/cache is only 1GB in my home laptop but it is 18GB in production server below.
Question2. To know the free RAM available to the system, Can I trust the 'available' column rather than the 'free' column ?
In my home laptop, the 'free' column shows 13GB and available shows 14GB
But, in my production server, when the free command shows just 2GB , the available command shows 9 GB
My Home Laptop with 16 GB RAM (Fedora 26)
A production Server (VM) with 24GB RAM (RHEL 7.4)
I know that free command displays memory usages however I like to know how the option and the results when I use this command..
PLease respond ASAP
thanx... I am a newbie.. :D (1 Reply)
Hi there again,
Running Solaris 10 with built-in Java. Seems to compile and run fine.
Problem is: Say I want to see contents of current directory. In a shell, I'd just write "ls" and it outputs the content.
When I write a Java file, I have the following line:
System.out.println("ls");
... (1 Reply)
Hi All
I have something that from the outset seems really trivial but in practice is not quite working.
I have the following code sample in my shell script which illustrates the problem
echo "enter home directory"
read home
mkdir $home/newdir
The user then enters a logical $HOME... (3 Replies)
hi all,
when I run-
wcars1j5#netstat -an | grep 8090
127.0.0.1.8090 *.* 0 0 49152 0 LISTEN
wcars1j5#
1. does this mean that no one is connected to this port?
Regards,
akash (1 Reply)
I am having trouble figuring this one out.....Is this a 2CPU or a 4CPU v490 with 16GB? I think it is a 2CPU system, looking for confirmation.
$ prtdiag
System Configuration: Sun Microsystems sun4u Sun Fire V490
System clock frequency: 150 MHz
Memory size: 16384 Megabytes
... (1 Reply)
Hello, I need some help to interpret the below output...
What is -/+ buffers/cache?
My understanding is, total RAM is 3986152 Bytes, used RAM is 3950904 bytes.
What is buffers and cached?? Can any one please interpret this output? It would be great help if some one can help me on this?
... (2 Replies)
Hi Friends,
I am really confused with the output of "free" command on redhat linux.
I can see caching and buffer output on two different areas on the output.
Please let me know whats the difference of these two different outputs.
Here I am pasting the command output of my server.
# free... (3 Replies)
Hi. I wonder what the equal sign in front of the answer means.
I have read man pages and googled but found no answer.
xntpdc -p
=15.5.64.3 15.5.2.51 3 512 377 0.02060 0.057426 0.04965Thanks.
Jan (1 Reply)
Hi All,
I have a file with name
Is there a LINUX command that will help me to output the word after the 9th Underscore(_).
ie the output should be DLY in this case.
Can anybody pls help me.
Thanks much in advance,
Freddie (4 Replies)
I wanted to know the concept of free -m command as there are different rows of Mem, -/+ buffers/cache & Swap in the output. As an example, it is showing 195 as free Mem in my server but 13850 in the free section of the -/+ buffers/cache row. The output needs in depth knowledge of the different... (7 Replies)
Discussion started by: RHCE
7 Replies
LEARN ABOUT LINUX
slabinfo
SLABINFO(5) Linux Programmer's Manual SLABINFO(5)NAME
/proc/slabinfo - Kernel slab allocator statistics
SYNOPSIS
cat /proc/slabinfo
DESCRIPTION
Frequently used objects in the Linux kernel (buffer heads, inodes, dentries, etc.) have their own cache. The file /proc/slabinfo gives
statistics. For example:
% cat /proc/slabinfo
slabinfo - version: 1.1
kmem_cache 60 78 100 2 2 1
blkdev_requests 5120 5120 96 128 128 1
mnt_cache 20 40 96 1 1 1
inode_cache 7005 14792 480 1598 1849 1
dentry_cache 5469 5880 128 183 196 1
filp 726 760 96 19 19 1
buffer_head 67131 71240 96 1776 1781 1
vm_area_struct 1204 1652 64 23 28 1
...
size-8192 1 17 8192 1 17 2
size-4096 41 73 4096 41 73 1
...
For each slab cache, the cache name, the number of currently active objects, the total number of available objects, the size of each object
in bytes, the number of pages with at least one active object, the total number of allocated pages, and the number of pages per slab are
given.
Note that because of object alignment and slab cache overhead, objects are not normally packed tightly into pages. Pages with even one in-
use object are considered in-use and cannot be freed.
Kernels compiled with slab cache statistics will also have "(statistics)" in the first line of output, and will have 5 additional columns,
namely: the high water mark of active objects; the number of times objects have been allocated; the number of times the cache has grown
(new pages added to this cache); the number of times the cache has been reaped (unused pages removed from this cache); and the number of
times there was an error allocating new pages to this cache. If slab cache statistics are not enabled for this kernel, these columns will
not be shown.
SMP systems will also have "(SMP)" in the first line of output, and will have two additional columns for each slab, reporting the slab
allocation policy for the CPU-local cache (to reduce the need for inter-CPU synchronization when allocating objects from the cache). The
first column is the per-CPU limit: the maximum number of objects that will be cached for each CPU. The second column is the batchcount:
the maximum number of free objects in the global cache that will be transferred to the per-CPU cache if it is empty, or the number of
objects to be returned to the global cache if the per-CPU cache is full.
If both slab cache statistics and SMP are defined, there will be four additional columns, reporting the per-CPU cache statistics. The
first two are the per-CPU cache allocation hit and miss counts: the number of times an object was or was not available in the per-CPU cache
for allocation. The next two are the per-CPU cache free hit and miss counts: the number of times a freed object could or could not fit
within the per-CPU cache limit, before flushing objects to the global cache.
It is possible to tune the SMP per-CPU slab cache limit and batchcount via:
echo "cache_name limit batchcount" > /proc/slabinfo
FILES
<linux/slab.h>
VERSIONS
/proc/slabinfo exists since Linux 2.1.23. SMP per-CPU caches exist since Linux 2.4.0-test3.
NOTES
Since Linux 2.6.16 the file /proc/slabinfo is only present if the CONFIG_SLAB kernel configuration option is enabled.
COLOPHON
This page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
2007-09-30 SLABINFO(5)