Re: moving buffers/caching from RAM to SSD

[Stan Hoeppner <stan@hardwarefreak.com>]

On 12/31/2013 7:54 AM, Muhammad Yousuf Khan wrote:
> i dont know why i am saying is even practical or not.
> 
> here is my free command
> 
> @thor:# free -g
>              total       used       free     shared    buffers     cached
> Mem:            31         31          0          0          0         26
> -/+ buffers/cache:          3         27
> Swap:           93          0         93
> 
> 
> as you can see 27GB is being used in caching. i have few 160GB SSDs.
> can i move this buffers/caching load to my SSD. so that things could work
> more better.

Muhammad,

By design, the Linux kernel will use nearly all free memory for caching
disk blocks and filesystem metadata when the memory isn't needed by
other processes.

When a process needs memory, the kernel simply drops some of the cached
pages, freeing them for immediate use.  This process takes a few tens of
nanoseconds per 4KB page--it is instantaneous.  It is because these
pages can be freed instantly that Linux eats up all the RAM for cache.
Cached file access is hundreds of times faster than disk access, even if
disk is SSD.

What you are seeing is the expected Linux kernel behavior.  There is
nothing wrong here, nothing to fix.

-- 
Stan