Mentioned parameter controls whether memory reclaim is performed on a local NUMA node even if there is a plenty of memory free on other nodes. Is other than 0, there is a chance to be affected by a memory issue described above (not all available physical memory is used). It is possible to check whether there is more than one memory node. One memory node in the system is too far beyond access of a particular CPU than its local memory node. Such situation can happen on NUMA (Non-Uniform Memory Access) hardware. Another situation which can happen is that system is not using all available physical RAM. Taking more snapshots of the file (say every 1-2 seconds) while there is a suspected misbehavior might help identifying problems in the kernel memory management implementation under particular load.Ģ.
When the result of this formula does show enough memory, then the system is handling the memory in a good way, and there is no reason to be concerned about the memory usage. Inactive - Dirty = amount of memory which can be dropped/reclaimed in case that it will be needed by other processes Inactive (amount of buffer/page cache memory which is not in active usage - can be reclaimed for other actions)ĭirty - amount of memory waiting to be written to disk MemFree (amount of physical RAM which is unused by the system)Ĭached (amount of physical RAM used as cache memory)Īctive (amount of buffer/page cache memory which is in active usage - usually not reclaimed for other actions) There are many counters in the output but the one that are helping to decide whether the system is running well are the following: Which displays a snapshot of memory usage (in KBs) from the moment when the command was triggered. In order to check whether the system is running correctly in regards to memory, it is possible to do that by checking the output of the following cat /proc/meminfo
However, when the system is not using available memory, there is most probably something wrong. In case if the system cannot satisfy memory requirements of new or greedy processes, then the kernel will start dropping some page cache to free the necessary amount of memory for them. Unless some of the symptoms described below occurs, the system is handling memory efficiently.įor example, it holds the data which are often in use in memory page cache to provide fast access to those data, as access to memory is much faster in comparison to a disk access. Operating system itself manages all available memory in a very efficient way and from user perspective the memory management is fully automated. In case that this is the scenario, there is no reason to be worried. "free" command displays just a small portion of free free -m There are concerns about the amount of free memory as e.g.
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