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 CENTOS
free
FREE(1) User Commands FREE(1)NAME
free - Display amount of free and used memory in the system
SYNOPSIS
free [options]
DESCRIPTION
free displays the total amount of free and used physical and swap memory in the system, as well as the buffers and caches used by the ker-
nel. The information is gathered by parsing /proc/meminfo. The displayed columns are:
total Total installed memory (MemTotal and SwapTotal in /proc/meminfo)
used Used memory (calculated as total - free)
free Unused memory (MemFree and SwapFree in /proc/meminfo)
shared Memory used (mostly) by tmpfs (Shmem in /proc/meminfo, available on kernels 2.6.32, displayed as zero if not available)
buffers
Memory used by kernel buffers (Buffers in /proc/meminfo)
cached Memory used by the page cache (calculated as Cached - Shmem in /proc/meminfo - the Cached value is actually the sum of page cache
and tmpfs memory)
OPTIONS -b, --bytes
Display the amount of memory in bytes.
-k, --kilo
Display the amount of memory in kilobytes. This is the default.
-m, --mega
Display the amount of memory in megabytes.
-g, --giga
Display the amount of memory in gigabytes.
--tera Display the amount of memory in terabytes.
-h, --human
Show all output fields automatically scaled to shortest three digit unit and display the units of print out. Following units are
used.
B = bytes
K = kilos
M = megas
G = gigas
T = teras
If unit is missing, and you have petabyte of RAM or swap, the number is in terabytes and columns might not be aligned with header.
-c, --count count
Display the result count times. Requires the -s option.
-l, --lohi
Show detailed low and high memory statistics.
-o, --old
Display the output in old format, the only difference being this option will disable the display of the "buffer adjusted" line.
-s, --seconds seconds
Continuously display the result delay seconds apart. You may actually specify any floating point number for delay, usleep(3) is
used for microsecond resolution delay times.
--si Use power of 1000 not 1024.
-t, --total
Display a line showing the column totals.
--help Print help.
-V, --version
Display version information.
FILES
/proc/meminfo
memory information
SEE ALSO ps(1), slabtop(1), top(1), vmstat(8).
AUTHORS
Written by Brian Edmonds.
REPORTING BUGS
Please send bug reports to <procps@freelists.org>
procps-ng September 2011 FREE(1)