12/13/2023 0 Comments Linux list processes by memory usage![]() Free: The amount of remaining (unused) swap space.Used: The amount of swap space that's in use.Total: The size of the swap partition or file.The Swap columns contain the following information: Available: This is an estimate of the memory that's available to service memory requests from applications and any other operational software on your computer.This can be released quickly by the kernel if required. Buff/cache: Amount of memory used for buffers and cache.Shared: Amount of memory used by the tmpfs file systems.Used: The sum of Free+Buffers+Cache subtracted from the total amount.Total: The total amount of physical RAM on this computer.The Mem columns contain the following information: Total used free shared buff/cache available Value sets a threshold for RAM usage that triggers swap to be enabled.īut now, let's look at the different techniques you can use in the terminal window to see the RAM usage on your Linux computer. Value in Linux and when the kernel will start using swap. There's a lot of confusion about the swappiness If the kernel decides it's more efficient to start using swap space, it brings that into play, as well. If there are other demands for the RAM that the kernel has poached for its own devices, it relinquishes the memory instantly, so there's no harm done. It's usually just the kernel tenaciously doing its job in the background. It's easy to get the impression that your system's RAM has been consumed by some runaway process or memory leak, but that's rarely the case. Linux uses any spare RAM for things like file buffer space, to keep your computer running at optimum performance. It's kind of like a mother bird with more open beaks pointed at her than she has the grub for. The kernel referees the memory squabbles and allocates the rationed memory out to all the hungry processes. RAM is a finite resource that all processes, like applications and daemons, want a piece of. We'll also look at reading /proc/meminfo directly. In this roundup, we'll cover the most commonly used command-line methods: free, vmstat, and top. I’m seeing 6.7 GB of RAM being used, if i consider buffer and cache.There are plenty of ways you can get the lowdown on memory usage within your Linux system. If you set 150%/200%, what do we do about OOM events? It explodes way BEFORE reaching those values.Įxplain to me this !!! This is another server.Ĭheck_mk → 2.99 GB used (2.88 RAM + 0.08 SWAP + 0.02 Pagetables, this is 38.9% of 7.69 RAM (2.00 total SWAP), 15 min average 38.9%, 0.0 mapped, 1.1 committed, 0.0 sharedĢ.88 GB of ram? How does it do the calculation? Where does that came from? That’s more than 100%.Īnd, it says: 3.72 GB, not 6 GB. Well, it’s says 3.72 GB / 96,5% of RAM being used. You said that “Looking at swap and RAM separately makes no sense at all”. ![]() If i have 4 GB of ram and 2 GB of swap, check_mk sees only 4 GB of ram. RSS does not take in cosideration buffer/cache, dirty pages, pagetables. Why did you do that? why don’t you just take into consideration only processes memory? That means that this check gets critical if the memory used by processes is twice the size of your RAM. You define levels in percentage of the physically installed RAM or as absolute values in MB. So when defining a level to check against, the only value that is not affected by such internals of memory management is the total amount of virtual memory used up by processes (not by disk buffers). That is because Linux has taken RAM from processes in order to increase disk buffers. ![]() It does this in situations where disk buffers (are assumed to) speed up the overall performance more than keeping rarely used parts of processes in RAM.įor example after a complete backup of your system you might experiance that your swap usage has increased while you have more RAM free then before. ![]() Linux tends to swap out parts of processes even if RAM is available. In fact it is the only way to do it right (at least for Linux): What parts of a process currently reside in physical RAM and what parts are swapped out is not related in a direct way with the current memory usage. You can define a warning and critical level for the usage of virtual memory, not for the usage of RAM. The check measures the current usage of physical RAM and virtual memory used by processes. Why CMK is taking into the calculation cache & buffer values? Total used free shared buff/cache availableĬRIT - 3.59 GB used (2.89 RAM + 0.67 SWAP + 0.03 Pagetables, this is 96.5% of 3.72 RAM (2.00 total SWAP), 15 min average 96.4%, critical at 96.0% used, 0.0 mapped, 1.7 committed, 0.2 sharedĬritical? Only 836 MB are being used. I don’t know if this was already discussed (may be a thousand times):
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