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Top Forums UNIX for Beginners Questions & Answers Interpreting Linux's free command output Post 303010968 by drysdalk on Thursday 11th of January 2018 07:36:35 AM
Old 01-11-2018
Hi,

Taking your questions in turn:

1. Buffers and cache are essentially types of memory that, whilst they are in use, could be freed up if the system required memory for some other purpose. These are types of memory that are mostly used to hold things which either are yet to be written or have recently been read from disk, in order to accelerate file I/O. So if ever a process genuinely needs more memory than is sitting absolutely unused (which is the total in the 'free' column) more can be obtained by flushing out certain things from the buffers and/or cache.

2. The 'free' column shows you the memory on the system which is genuinely 100% unused - so not in use by a process, and not part of the buffers, cache or shared memory pool. The 'available' column consists of the 'free' memory, plus whatever memory from other categories (mainly the buffers and cache) which could be easily freed up if required. So you can take 'available' as a trustworthy figure as the amount of free memory that applications could use if they needed to.

Hope this helps.
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WINCACHE_UCACHE_MEMINFO(3)						 1						WINCACHE_UCACHE_MEMINFO(3)

wincache_ucache_meminfo - Retrieves information about user cache memory usage

SYNOPSIS
array wincache_ucache_meminfo (void ) DESCRIPTION
Retrieves information about memory usage by user cache. RETURN VALUES
Array of meta data about user cache memory usage or FALSE on failure The array returned by this function contains the following elements: o memory_total - amount of memory in bytes allocated for the user cache o memory_free - amount of free memory in bytes available for the user cache o num_used_blks - number of memory blocks used by the user cache o num_free_blks - number of free memory blocks available for the user cache o memory_overhead - amount of memory in bytes used for the user cache internal structures EXAMPLES
Example #1 A wincache_ucache_meminfo(3) example <pre> <?php print_r(wincache_ucache_meminfo()); ?> </pre> The above example will output: Array ( [memory_total] => 5242880 [memory_free] => 5215056 [num_used_blks] => 6 [num_free_blks] => 3 [memory_overhead] => 176 ) SEE ALSO
wincache_fcache_fileinfo(3), wincache_fcache_meminfo(3), wincache_ocache_fileinfo(3), wincache_rplist_fileinfo(3), wincache_rplist_mem- info(3), wincache_refresh_if_changed(3), wincache_ucache_info(3), wincache_scache_info(3), wincache_scache_meminfo(3). PHP Documentation Group WINCACHE_UCACHE_MEMINFO(3)
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