Great .. you found more details..
--- In [email protected], "Prashant Karmankar" <[EMAIL PROTECTED]> wrote: > RedHat Explanation >>>> > > http://kbase.redhat.com/faq/FAQ_80_705.shtm > > Resolution: > > The philosophy in Linux is that an unused resource is a wasted > resource. The kernel therefore will use as much RAM as it can to cache > information from your local and remote filesystems/disks. This builds > up over time as reads and writes are done on the system trying to keep > the data stored in RAM as relevant as possible to the processes that > have been running on your system. This caching is reported by the > system as the sum of two numbers, buffers and pagecache. The cache is > reclaimed, not at the time of process exit (you might start up another > process soon that needs the same data), but upon demand - i.e. When > you start a process that needs a lot of memory to run, the Linux > kernel will reclaim memory that had been storing cached data and give > it to the new process. > > There are some things which get reported as cache which are not > directly freeable by the kernel, such as anonymous mmaps and shm > regions. These will however, report against all processes attached to > them unlike normal cache which is not part of the address space of any > running process but is simply a kernel mapping. > > For example (Units are in megabytes): > > > # free -m > total used free shared buffers cached > Mem: 1000 900 100 0 350 350 > -/+ buffers/cache: 200 800 > > In this example, as far as applications are concerned the system is > using only 200MB of memory and has 800MB free and available for use if > needed. > > The items to note here are: > > > <Physically Used Memory> = <Actual used memory> + <buffers> + <cache> > > <Physically Free Memory> = <Total Physical Memory> - <Actual used > memory> - <buffers> - <cache> > > <Memory free for Applications> = <Total Physical Memory> - <Actual > used memory> > > <Memory used by Applications> = <Actual used memory> - <buffers> - > <cache> > > Regards > > Prashant K >
