I have made the observation that the Linux kernel has performance hick-ups if there is continuous I/O.
This has to do with buffering all and everything, according to the dogma "every unused byte of memory is wasted memory". If allocation happens too fast, freeing buffers can take a long time.
But the term "memory fragmentation" does not fit here.
All commercial Unix kernels have configurable limits for buffers and caches; and behave smoothly in such a situation (and little slower in others).
In the very past I had a SuSE PAE kernel that even invoked OOM-killer at continuous I/O. The following program, invoked every 5 minutes, helped: ---------- Post updated at 06:56 AM ---------- Previous update was at 03:14 AM ----------
In the case of a 64-bit kernel only the following should be called every 5 or 10 minutes:
In addition try to write smaller portions of data to the disk, in /etc/sysctl.conf:
Last edited by MadeInGermany; 09-14-2014 at 12:28 PM..
Hello:
Environment is: Oracle 817 on IBM RS/6000 AIX 433
I have 4GB RAM on the box and Page/Swap is about the same.
Presently I am using close to 1GB of RAM towards 5 instances of ORACLE production environments.
How can I know, how much of memory/RAM is used for :
Oracle Processes , I... (2 Replies)
HI All,
I need a script to reboot a linux box from a windows box.
The script needs to run automatically whenever a sitescope alerts with an error message.
Have searched for this in the forums, but could not get something relative.
Pls. let me know the various alternatives we have to do... (2 Replies)
hi,
if I do top, I get
Memory: 19277012K (5868296K) real, 33860312K (11294208K) virtual, 795392K free
If I do swapinfo -tm I get:
% swapinfo -tm
Mb Mb Mb PCT
TYPE AVAIL USED FREE USED
dev 16384 0 16383 0%
dev ... (3 Replies)
Hi
I'be recently installed Virtouzzo on Centos 5 on 16GB box , but the system could only see 4 GB of RAM, I installed the package kernel-PAE, but the virtuozzo kernel still can't see the full memory.
even the kernel system can see 16GB of RAM
is there any idea bout that ?
Thanks (2 Replies)
I have certain questions.
1) How can i see the memory of the unix box.
2) How can i see the size of the database on the box
3)can anyone suggest an article or tutorial that explains the concept of
file systems and mount point in UNIX.
4)How can i see the dblink on the server
I... (5 Replies)
my system has 128G of installed memory. top, vmstat shows the system has just over 10G of free memory on the system. but as per prstat o/p the usage is just 50-55G is there anyway i can find which process/zone is using more memory ?
System has 3 zones and all running application servers.
... (1 Reply)
Hi,
I've been able to mount my linux box to a windows machine, but I can't seem to mount my linux box to another linux box I have. (I know I could scp, but for other reasons I need to do it this way) Samba is installed.
Here is an example where I mount to a Win machine.--> works fine
mount... (12 Replies)
Hi
I have a linux box and need to access from windows graphically
# uname -a
Linux pc-l416116 2.6.18-155.el5 #1 SMP Fri Jun 19 17:06:47 EDT 2009 i686 i686 i386 GNU/Linux
What components do I need to install on Linux and windows to do that?
TIA (6 Replies)
Hello my dear friends,
Two file are auto generated from mon - fri at different directories on same windows box.Every day i have to copy the file, rename it (specific name)and ftp it to linux box specified directory.
is it possible to automate this process,If yes this has to be done from windows... (1 Reply)
Discussion started by: umesh yadav
1 Replies
LEARN ABOUT DEBIAN
slabtop
SLABTOP(1) User Commands SLABTOP(1)NAME
slabtop - display kernel slab cache information in real time
SYNOPSIS
slabtop [options]
DESCRIPTION
slabtop displays detailed kernel slab cache information in real time. It displays a listing of the top caches sorted by one of the listed
sort criteria. It also displays a statistics header filled with slab layer information.
OPTIONS
Normal invocation of slabtop does not require any options. The behavior, however, can be fine-tuned by specifying one or more of the fol-
lowing flags:
-d, --delay=N
Refresh the display every n in seconds. By default, slabtop refreshes the display every three seconds. To exit the program, hit q.
-s, --sort=S
Sort by S, where S is one of the sort criteria.
-o, --once
Display the output once and then exit.
-V, --version
Display version information and exit.
-h, --help
Display usage information and exit.
SORT CRITERIA
The following are valid sort criteria used to sort the individual slab caches and thereby determine what are the "top" slab caches to dis-
play. The default sort criteria is to sort by the number of objects ("o").
The sort criteria can also be changed while slabtop is running by pressing the associated character.
character description header
a number of active objects ACTIVE
b objects per slab OBJ/SLAB
c cache size CACHE SIZE
l number of slabs SLABS
v number of active slabs N/A
n name NAME
o number of objects OBJS
p pages per slab N/A
s object size OBJ SIZE
u cache utilization USE
COMMANDS
slabtop accepts keyboard commands from the user during use. The following are supported. In the case of letters, both cases are accepted.
Each of the valid sort characters are also accepted, to change the sort routine. See the section SORT CRITERIA.
<SPACEBAR>
Refresh the screen.
Q Quit the program.
FILES
/proc/slabinfo
slab information
SEE ALSO free(1), ps(1), top(1), vmstat(8)NOTES
Currently, slabtop requires a 2.4 or later kernel (specifically, a version 1.1 or later /proc/slabinfo). Kernel 2.2 should be supported in
the future.
The slabtop statistic header is tracking how many bytes of slabs are being used and it not a measure of physical memory. The 'Slab' field
in the /proc/meminfo file is tracking information about used slab physical memory.
AUTHORS
Written by Chris Rivera and Robert Love.
slabtop was inspired by Martin Bligh's perl script, vmtop.
REPORTING BUGS
Please send bug reports to <procps@freelists.org>
procps-ng June 2011 SLABTOP(1)