Problem in clearing up cache when it reaches half of ram size

LittleMaster · 08-23-2012, 02:30 AM

Dear All
Im currently the following running following command

sudo sync && sudo sysctl -w vm.drop_caches=3 && sudo sysctl -w vm.drop_caches=0

very half hour to clear cache of my server .Im currently trying to clear cache when it reaches only half of my Ram size .Any help regarding it how can i execute these command when it reach half of my ram size

[root@localhost ~]# free -m
total used free shared buffers cached
Mem: 3823 535 3288 0 41 351
-/+ buffers/cache: 142 3680
Swap: 6047 0 6047

evo2 · 08-23-2012, 02:38 AM

Hi,

why do you want to do this?

Evo2.

johnsfine · 08-23-2012, 06:31 AM

Quote:

Originally Posted by LittleMaster

Im currently trying to clear cache when it reaches only half of my Ram size .

Quote:

Originally Posted by evo2

why do you want to do this?

My opinion is probably implied by evo2's question, but making it more explicit:

A lot of Linux users think there is some good reason to stop the cache from filling the rest of memory (beyond what is used for everything else). In almost all cases THEY ARE WRONG.

unSpawn · 08-23-2012, 07:24 AM

Quote:

Originally Posted by johnsfine

A lot of Linux users think there is some good reason to stop the cache from filling the rest of memory (beyond what is used for everything else). In almost all cases THEY ARE WRONG.

...and to expand upon that: that's because they don't know the Linux kernel has a Virtual Memory Manager (VMM) that works OK ninety nine percent of the time for most purposes. Yes, there's a lot of VMM-related sysctls that can be tweaked but doing so before having baseline SAR stats and having pinpointed the bottleneck(s) makes no sense.

chrism01 · 08-23-2012, 07:54 PM

@OP: as with the above comments, you (almost definitely) don't want to be doing that.
Try reading this
http://www.linuxatemyram.com/