How to get the actual memory utilization?

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Hi,

I would like to know is there any command or tricks to get the actual memory utilization without confuse with buffer and cache utilization? I wanted to know the actual utilization and free space of my memory.

As for now, I'm using "free -m" command, but I need to minus the buffer and cache to get the actual utilization. It there any ways to get the information?

I got this understanding from this link :

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/5/html/Tuning_and_Optimizing_Red_Hat_Enterprise_Linux_for_Oracle_9i_and_10g_Databases/chap-Oracle_9i_and_10g_Tuning_Guide-Memory_Usage_and_Page_Cache.html

Thank you very much for your kindness!

MA
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Responses

Jamie Bainbridge's picture Red Hat Guru 7252 points
26 May 2016 4:01 AM

What is the reason you're interested in the measurement? Are you wondering if the system is using all its available RAM and you could add more or remove some, do you wish to know how much space is available for additional programs to run, or for some other reason?

As the page you linked to explains, what is considered "used" and "available" depends on what your purpose is.

MA Newbie 10 points
26 May 2016 6:24 AM

Thank you Jamie, I interested in measurement because I would like to know the actual memory utilization and also to plan for capacity planning.

I also used "sar command" to get the memory utilization info, but there is also buffer and cache information. Did I need to minus the buffer and cache to get the actual memory utilization? because the link that I shared is explain like that.

Thank you for your time.

Jamie Bainbridge's picture Red Hat Guru 7252 points
26 May 2016 6:40 AM

If you subtract cache from total RAM, that gives you an indication of how much RAM is available for applications. Yes, this is the same in free and sar.

Note that shared memory and tmpfs will also count as cache, so if you use these things you need to consider them.

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