An awesome reply. Makes sense! Thanks. On Tue, Aug 19, 2008 at 9:42 AM, David Dyer-Bennet <dd-b at dd-b.net> wrote: > > 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) > > It's very likely being used as disk cache. You can get some more numbers > 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. > > > 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 > > applications are eating up the cache?* > > 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 at dd-b.net; http://dd-b.net/ > Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/ > Photos: http://dd-b.net/photography/gallery/ > Dragaera: http://dragaera.info > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.centos.org/pipermail/centos/attachments/20080819/97ff6c7b/attachment-0004.html>