The Memory Usage utility provides statistics for the physical memory installed, used, and available on each system card.
The following table lists the memory usage fields.
Memory Usage Fields Description
| Attribute | Description |
|---|---|
| Active | Memory that has been recently used and is usually not reclaimed unless required. |
| Active(anon) | Anonymously used memory. |
| Active(file) | Memory associated with a file. |
| AnonHugePages | Non-file backed huge pages mapped into userspace page tables. |
| AnonPages | Memory associated with these pages. |
| Bounce | Shows bounce buffers. Some file systems allow you to dirty pages while they are being written. If your device requires stable pages, this allocates a page, copies the dirty page into it, and writes the copy to disk in order make sure it is stable. |
| Buffers | The amount of physical RAM, in kilobytes, used for file buffers. |
| Cached | Memory used by the page cache (diskcache) minus SwapCache. |
| Commited_AS | Memory that is currently committed. Shows all of the malloc()'s added up. |
| CommitLimit | Allows you to malloc() up to the CommitLimit before malloc() returns -ENOMEM. |
| DirectMap2M | x86-specific: available 2M direct-mapped slots. |
| DirectMap4k | x86-specific: available 4K direct-mapped slots. |
| DirectMap1G | x86-specific: available 1G direct-mapped slots. |
| Dirty | Pagecache pages that are dirty, waiting to be written to disk. |
| HardwareCorrupted | ECC-detected errors. |
| HugePages_Free | The number of huge pages in the pool that are not yet allocated. |
| HugePages_Rsvd | HugePages_Rsvd is short for "reserved," and is the number of huge pages for which a commitment to allocate from the pool has been made, but no allocation has yet been made. Reserved huge pages guarantee that an application is able to allocate a huge page from the pool of huge pages at fault time. |
| HugePages_Total | Total is the size of the pool of huge pages. |
| Hugepagesize | The size of each hugepage on this system. |
| HugsPages_Surp | HugePages_Surp is short for "surplus," and is the number of huge pages in the pool above the value in /proc/sys/vm/nr_hugepages. The maximum number of surplus huge pages is controlled by /proc/sys/vm/nr_overcommit_hugepages. |
| Inactive | Inactive memory can be memory that is being used by applications and have been opened (but has not been in awhile, so it is inactive instead of active) or it can be memory that has been used by a previously opened application. |
| Inactive(anon) | Inactive anonymously used memory. |
| Inactive(file) | Inactive memory associated with file. |
| KernelStack | Pages used for kernel stack space. |
| Mapped | Number of file backed mmap()'ed pages. |
| Mem | The total amount of free and used physical and swap memory in the system, as well as the buffers used by the kernel. Note
Not supported. |
| MemAvailable | Estimate of how much memory is available for starting new applications, without swapping. Among other things, it is calculated from MemFree, SReclaimable, the size of the file LRU lists, and the low watermarks in each memory zone. The estimate takes into account that the system needs some page cache to function well, and that not all reclaimable slab will be reclaimable, due to items being in use. |
| MemFree | The sum of LowFree and HighFree memory, in kilobytes (overall statistic). |
| MemTotal | Total usable RAM, in kilobytes, (that is, physical RAM minus a few reserved bits and the kernel binary code). |
| Mlocked | The amount of allocated memory that is strictly prohibited from being paged out. |
| NFS_Unstable | NFS pages sent to the server, but not yet committed to stable storage. |
| PageTables | Memory dedicated to the lowest level of page tables. |
| Shmem | Size of shared memory, anybody who did mmap() with MAP_SHARED | MAP_ANONYMOUS. |
| Slab | In-kernel data structures cache. |
| SReclaimable | Part of Slab that might be reclaimed, such as caches. |
| SUnreclaim | Part of Slab that cannot be reclaimed on memory pressure. |
| Swap | Disk space that is temporarily used to hold pages of memory that are not currently in RAM. Note
Not supported. |
| SwapCached | Memory that once is swapped out and is swapped back in but still also is in the swapfile (if memory is needed it does not need to be swapped out AGAIN, because it is already in the swapfile). |
| SwapFree | Total amount of swap memory free. |
| SwapTotal | Total amount of physical swap memory. |
| Unevictable | These pages are pinned and cannot be swapped or reclaimed. Includes kernel pages and Mlocked pages. |
| VmallocChunk | The largest contiguous block of memory, in kilobytes, of available virtual address space. |
| VmallocTotal | The total amount of memory, in kilobytes, of total allocated virtual address space |
| VmallocUsed | The total amount of memory, in kilobytes, of used virtual address space. |
| Writeback | The total amount of memory, in kilobytes, actively being written back to the disk. |
| WritebackTmp | Used for FUSE, it is the same thing as Writeback or NFS_Unstable, just FUSE-ified |
To view memory usage
- From the Main Menu, click Processes.
- Click Memory Usage.
- Using the Memory Usage on drop-down list, select the system card that you want to obtain memory usage information about.
- Click Update.
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