Red Hat Bugzilla – Bug 145319
Low free Memory
Last modified: 2007-11-30 17:07:06 EST
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Description of problem:
Output from free -m:
[root@r2pgardel log]# free -m
total used free shared buffers
Mem: 2007 1931 75 0 132
-/+ buffers/cache: 167 1839
Swap: 4000 0 4000
This during low load and 1 user. Why is the percantage of free memory
so smal? Tried to tune the memory usage with via the /etc/sysctl.conf
file. IÂ´ve succeeded in raising the inactive_clean_percent to 40 but
when I try to change bdflush with the following line in sysctl.conf:
vm.bdflush="30 700 0 0 400 2500 70
It still states the default values after reboot. Even if I issue the
command sysctl -p it persists!
Version-Release number of selected component (if applicable):
Steps to Reproduce:
Expected Results: Freeing memory.
The value of free memory varies between 50 - 100 MB. This is
unchanged if I start a lot of applications so the kernel (2.4.21-
27.0.1.ELsmp) seems to free memory as it should. IÂ´m still a bit
worried about the low memory avialable...
Hi - this question gets asked a lot.
"Free memory" is found in two places... there's some on the 'Mem: '
line and some more on the "+/- buffers/cache: "
If you look at the free on the top line it looks alarming. The free
on second line is less so.
The Linux kernel reserves most unused memory for use as internal
buffers and filesystem buffer cache. The first line reports:
Total: how much physical memory the machine has
Used: amount of used (kernel + user + buffers + cache) memory
Free: how much unallocated memory
Shared: how much is shared via shm, mmap, shlibs, etc.
Buffers: how much is preallocated to unused kernel buffers
Cached: how much is preallocated to unsued filesystem buffer cache
The second line reports:
Used: amount of system memory that is actually in use
this is the first line 'used' - (buffers + cache)
Free: amount of memory that isn't actually busy
this is the first line 'free' + buffers + cache.
From your free listing I see that you have 1839M of your 2007M free.
You're doing great! No need to worry.
Much better thank you! Feels much better to know that my mem is some