clear cache memory Post: 302707941

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Operating Systems Solaris clear cache memory Post 302707941 by achenle on Sunday 30th of September 2012 01:30:38 PM

09-30-2012

Registered User

Quote:

Originally Posted by maxim42

hi all,

i have noticed that my server has 64 GB RAM and i have application in this server but the server has free memory only 15% and utilized 85% however it didn't eat from swap .

does any parameter can be configured in kernel to make the system clear memory from cache like linux

i found this command for linux and it worked it free the memory in redhat i want something like this in solaris ?

Code:

sync; echo 3 > /proc/sys/vm/drop_caches

IIRC, that just drops file system caches. It's only useful for doing benchmarking to figure out how fast your system can access uncached data.

The only scenario I've ever seen where it made sense to restrict cache usage is when you know you're going to need memory later. In that case, you'd want to put limits on cache usage so that you don't run into performance issues when your server suddenly needs more RAM.

Because freeing a lot of cache doesn't happen immediately - it can take substantial time.

Where this can really causes problems is when your transient memory needs large memory pages. File system cache tends to fragment memory into smaller pages, and if you're tight on free memory because your server has a lot of cached data, a sudden demand for large pages can cause serious performance issues as it tries to free pages and coalesce them into the requested larger pages.

Something like an Oracle database system with multiple large ISM shared memory segments running on ZFS...

But even in that case, you want to limit the cache usage beforehand, not clear it afterwards. Because it will just go back up again like it's designed to do.

achenle

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LEARN ABOUT PHP

wincache_scache_meminfo

WINCACHE_SCACHE_MEMINFO(3)						 1						WINCACHE_SCACHE_MEMINFO(3)

wincache_scache_meminfo - Retrieves information about session cache memory usage

SYNOPSIS

       array wincache_scache_meminfo (void  )

DESCRIPTION

	Retrieves information about memory usage by session cache.

RETURN VALUES

	Array of meta data about session 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 session cache

	      o memory_free - amount of free memory in bytes available for the session cache

	      o num_used_blks - number of memory blocks used by the session cache

	      o num_free_blks - number of free memory blocks available for the session cache

	      o memory_overhead - amount of memory in bytes used for the session cache internal structures

EXAMPLES

       Example #1

	      A wincache_scache_meminfo(3) example

	      <pre>
	      <?php
	      print_r(wincache_scache_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).

PHP Documentation Group 												WINCACHE_SCACHE_MEMINFO(3)

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