Linux
--
Questions
--
Followers
Top Experts
how to free up ram on RHEL
Besides the obvious of upgrading RAM. is there a way to free up memory on RHEL 5 . As you see below we are maxed out
Tasks: 191 total, 1 running, 190 sleeping, 0 stopped, 0 zombie
Cpu(s): 49.2%us, 9.0%sy, 0.0%ni, 39.3%id, 1.5%wa, 0.1%hi, 0.9%si, 0.0%st
Mem: 16312904k total, 16260260k used, 52644k free, 22988k buffers
Swap: 18481144k total, 0k used, 18481144k free, 9246296k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
4855 ehsj 18 0 7186m 6.2g 10m S 409.6 40.1 110:35.36 java
4516 qpidd 16 0 487m 15m 3672 S 58.7 0.1 34:15.33 qpidd
808 root 10 -5 0 0 0 S 1.0 0.0 0:15.45 kjournald
464 root 15 0 0 0 0 S 0.3 0.0 0:03.67 pdflush
465 root 15 0 0 0 0 S 0.3 0.0 0:05.21 pdflush
466 root 10 -5 0 0 0 S 0.3 0.0 0:01.73 kswapd0
5066 ehsj 15 0 12740 1164 824 R 0.3 0.0 0:00.22 top
1 root 15 0 10348 708 592 S 0.0 0.0 0:02.39 init
2 root RT -5 0 0 0 S 0.0 0.0 0:00.01 migration/0
3 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/0
4 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/0
5 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/1
6 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/1
7 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/1
8 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/2
9 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/2
10 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/2
Tasks: 191 total, 1 running, 190 sleeping, 0 stopped, 0 zombie
Cpu(s): 49.2%us, 9.0%sy, 0.0%ni, 39.3%id, 1.5%wa, 0.1%hi, 0.9%si, 0.0%st
Mem: 16312904k total, 16260260k used, 52644k free, 22988k buffers
Swap: 18481144k total, 0k used, 18481144k free, 9246296k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
4855 ehsj 18 0 7186m 6.2g 10m S 409.6 40.1 110:35.36 java
4516 qpidd 16 0 487m 15m 3672 S 58.7 0.1 34:15.33 qpidd
808 root 10 -5 0 0 0 S 1.0 0.0 0:15.45 kjournald
464 root 15 0 0 0 0 S 0.3 0.0 0:03.67 pdflush
465 root 15 0 0 0 0 S 0.3 0.0 0:05.21 pdflush
466 root 10 -5 0 0 0 S 0.3 0.0 0:01.73 kswapd0
5066 ehsj 15 0 12740 1164 824 R 0.3 0.0 0:00.22 top
1 root 15 0 10348 708 592 S 0.0 0.0 0:02.39 init
2 root RT -5 0 0 0 S 0.0 0.0 0:00.01 migration/0
3 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/0
4 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/0
5 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/1
6 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/1
7 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/1
8 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/2
9 root 34 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/2
10 root RT -5 0 0 0 S 0.0 0.0 0:00.00 watchdog/2
Zero AI Policy
We believe in human intelligence. Our moderation policy strictly prohibits the use of LLM content in our Q&A threads.
I wouldn't say you're maxed out. You're not even touching swap. Java is the obvious culprit, in my opinion it's bloated and slow but you must be running it for a reason so that decision's already been made. What performance problems are you having, if any?
i was looking at this line 16312904k total, 16260260k used and thought we were using nearly all of the 16 gigs of memory. Is upgrading to 32 gig recommended?
If it ain't broke, don't fix it. I'm already in awe of a machine that has 16GiB. My guess would be you don't need it (won't notice much improvement if you get it), especially as you're not even touching swap. The memory usage includes file-backed pages it hasn't looked at in a long time. It will reclaim that memory when it needs it, and you won't notice any slowdown.
EARN REWARDS FOR ASKING, ANSWERING, AND MORE.
Earn free swag for participating on the platform.
My guess you are not using more than 5-6GB
Please post the output of the following command
free -m
Please post the output of the following command
free -m
total used free shared buffers cached
Mem: 15930 15876 54 0 20 8967
-/+ buffers/cache: 6888 9042
Swap: 18047 0 18047
Mem: 15930 15876 54 0 20 8967
-/+ buffers/cache: 6888 9042
Swap: 18047 0 18047
doesnt the above show used 15876 and only 54kb of free memory. looks like the alignment is off after i copied and paste
Get a FREE t-shirt when you ask your first question.
We believe in human intelligence. Our moderation policy strictly prohibits the use of LLM content in our Q&A threads.
Those figures are in MiB, so your total of 15930 is about 16MB. The "used" number on the second line (that excludes buffers/caches) is what is in use, if you ignore that cached pages that can be dropped if your applications need more memory. You don't really want much actual free memory, it would just be a waste, so they're filled with cached data most of which you probably don't need.
ASKER CERTIFIED SOLUTION
membership
Log in or create a free account to see answer.
Signing up is free and takes 30 seconds. No credit card required.
You have almost 9GB of free memory
The Line
-/+ buffers/cache: 6888 9042
Means you have 6.8 GB used and 9GB free
You are all fine , to understand this exactly read about ( buffer cache ) this is a concept in the Linux kernel that makes use of unused memory instead of leaving it wasted
The Line
-/+ buffers/cache: 6888 9042
Means you have 6.8 GB used and 9GB free
You are all fine , to understand this exactly read about ( buffer cache ) this is a concept in the Linux kernel that makes use of unused memory instead of leaving it wasted
Technicality: 6,888 mebibytes free is about 6.7 gibibytes or 7.2 gigabytes, and not 6.8 anything.
EARN REWARDS FOR ASKING, ANSWERING, AND MORE.
Earn free swag for participating on the platform.
Yup that is more accurate , I was just giving approximates
Linux handles memory management differently. Everything is cached to speed access if the same data is used twice. This memory is instantly available to any process that might need it. Freemem on an active system will almost always be about 50MB. This then means that the cached value reported by top or free is the actual amount of free memory.
With many later Linux distros there is a graphical display that shows the cached mem as part of the free - but it's not very useful for administration unless you have lots of time to sit and watch it.
With many later Linux distros there is a graphical display that shows the cached mem as part of the free - but it's not very useful for administration unless you have lots of time to sit and watch it.
Linux
--
Questions
--
Followers
Top Experts
Linux is a UNIX-like open source operating system with hundreds of distinct distributions, including: Fedora, openSUSE, Ubuntu, Debian, Slackware, Gentoo, CentOS, and Arch Linux. Linux is generally associated with web and database servers, but has become popular in many niche industries and applications.