![]() On the NI Linux Real-Time OS, you can also get helpful information about memory usage on the Real-Time target by opening /proc/meminfo directly from the target. /home/oracle> free total used free shared buffers cached Mem: 263750172 219060896 44689276 91608 797480 88062464 -/+ buffers/cache: 130200952 133549220 Swap: 16773116 505760 16267356. When we deploy a real-time application written using the LabVIEW Real-Time Module, we expect the LabVIEW process to use the largest amount of memory. To get an accurate account of memory usage, we can look at the process on the device that uses the most memory. It can be difficult to get a simple accounting of system memory usage due to how memory management and reporting is handled by the Linux OS.However, we can use the tools provided by the Linux OS to accurately monitor the memory usage on the real-time device. Memory management and reporting on Linux devices differs significantly from targets running operating systems such as Windows or VxWorks. To make any sense it should have been -/+ buffers+cached.Additional InformationOn NI Linux Real-Time OS targets, the Free Physical Memory Property Node of the System Configuration API along with the Distributed System Manager fail to give an accurate accounting of the free physical memory on the device. It is completely confusing to the average user. Please ignore the -/+ buffers/cache text. Now if you start asking how much memory is being used by a single process then the computation factoring in shared memory gets harder. These calculations make sense since if your processes ask for more memory, the kernel will happily free its buffers and cached resources and hand it over!įinally, the shared is not factored into the second line computation because it is memory that is already shared among the processes. How much of the used memory has been put up to use as buffers and cache is also shown in the first line.Ĭoncerned about how much memory is truly being used by processes you are running? That is why the confusing second line exists! used-in-second-line = used-in-first-line - buffers - cached and free-in-second-line = free-in-first-line + buffers + cached. Memory lying unused is useless, so kernel tries to use it as buffers and for caching. You should not get worried if you see the free number being low. The used and free entries in the first line show you how much RAM is being used and is free. These are the memory shared among processes, memory that is being used as buffers (temporary storage) by the kernel and as cached for pages. The next three columns are a bit more complicated. The first three columns seem straightforward: the total capacity, how much of the total is used by processes and how much of the total is free. The final line of numbers is about your swap space. The first two lines of numbers are concerned about RAM. Some notes about interpreting the output: Now we can read the value in GBs and MBs easily. We first fix that by asking it to show human readable output: $ free -human While this might have been fine back when Unix was invented, it is utterly unreadable with the GBs of RAM we have in today’s computers. Right off the bat you can see that it is showing values in bytes. ![]() You run it and it throws up some head-scratching output: $ free The command to check this in Linux is free. □ 2016-Jun-15 ⬩ ✍️ Ashwin Nanjappa ⬩ □️ free, memory ⬩ □ ArchiveĪ common question that occurs to any user of an operating system is how much memory is being used and how much is free.
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