How to Clear buffer/cache memory
Hi,
I have redhat 5.3 64bit. it has kernel 2.6.18-308.13.1.el5. it has showing all memory used in chache. [abc]$ free -m total used free shared buffers cached Mem: 24103 23965 137 0 16 2641 -/+ buffers/cache: 21308 2794 Swap: 8001 4176 3824 . please help me to get the memory in use. |
it IS "in use". If running applications need the space, they'll reclaim it. There is nothing to do.
you CAN do what you asked ... "sysctrl -w vm.drop_caches=3" BUT if you don't actually understand this already, don't do it. In a similar vein you can lower the "swappiness" value but these things work as they do by default for a reason, and most people have no valid reason to change them, including, I suspect, you. |
Wellll ...
Looking at that, out of 24 Gig RAM, more than 88% is in use (i.e. not buffer/cache). Maybe the OP has a reasonable request - what's using it. What does "top" show for a start ?. |
Top output is normal...
top - 13:13:12 up 5 days, 14:27, 2 users, load average: 2.45, 1.55, 1.01 Tasks: 461 total, 2 running, 459 sleeping, 0 stopped, 0 zombie Cpu(s): 5.1%us, 0.4%sy, 0.0%ni, 92.0%id, 2.4%wa, 0.0%hi, 0.1%si, 0.0%st Mem: 24681492k total, 24582896k used, 98596k free, 15576k buffers Swap: 8193140k total, 4787228k used, 3405912k free, 2882564k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 11724 oracle 18 0 3380m 105m 35m R 81.9 0.4 0:27.65 oracle 5489 oracle 16 0 3316m 17m 16m S 3.3 0.1 2:02.03 oracle 28181 oracle 18 0 3316m 10m 6972 S 2.3 0.0 27:07.90 oracle 18859 oracle 18 0 4348m 62m 53m S 0.7 0.3 32:48.52 oracle Acid--- Can I use this command on running server without downtime? |
Please reply.
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dropping caches shouldn't incur downtime, but from personal experience I've known it lock a box up on at least one occasion.
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