An awesome reply.
Makes sense!
Thanks.
Makes sense!
Thanks.
On Tue, Aug 19, 2008 at 9:42 AM, David Dyer-Bennet <dd-b@xxxxxxxx> wrote:
It's very likely being used as disk cache. You can get some more numbers
On Tue, August 19, 2008 11:31, ABBAS KHAN wrote:
> As by the time, I've learned that Linux works by caching apps by using a
> lot
> of RAM and then it reallocates the new stuff by cleaning the old cached
> pages from memory as compared to other OSs. With 2 gigs of RAM often I see
> the free memory only as 100-400MB. Using TOP or PS, it doesn't look like
> any
> program or process is using excessive memory (the highest process is seen
> with 1-2% total memory). *So, my questions are:*
>
> what programs are using that much of memory? (or cached memory)
by running top, and looking at the last two lines of the headers. I
routinely see over 1GB of cache on a not very active 4GB system. Your
meminfo output is the same numbers, and looks completely normal to me.
Free memory is *bad*; it means it's being wasted completely. Memory used
for disk caching is instantly available if it's suddenly needed for a
program.
> applications are eating up the cache?*
> Is that really due to a lot of cache in the memory
> *if yes, then, is there a way to parse the cache to findout what
It's only indirectly tied to an application; it's cached disk blocks. You
could say the process that read that file last is responsible, but the
*next* process to read those blocks is the one that would benefit.
> *how to free the cached memory?*
Why do you want to? As I said, "free" memory is memory that's going to
waste. Unless you have severe real-time issues with a process becoming
runnable where the difference between discarding a clean cached page, and
just allocating a free page, will make a difference, there's no point. If
you DO have that level really extreme real-time performance issues, you
need to understand the whole virtual memory system an order of magnitude
better than you seem to. That's off in a far corner of the Linux
application space -- Linux can do some real-time stuff, but it's not the
first choice for hard real-time environments last time I talked to any of
those people.
--
David Dyer-Bennet, dd-b@xxxxxxxx; http://dd-b.net/
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Dragaera: http://dragaera.info
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