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Thread: Buffers and caches in 2.6 kernel
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- Join Date
- Mar 2007
Buffers and caches in 2.6 kernel
free -m total used free shared buffers cached Mem: 2014 1769 244 0 12 110
My understanding is that the virtual filesystem implements 4 caches:
* page caching
* inode caching
* directory caching (d-cache)
* buffer caching
Actually, I've also read that these caches are implemented as one big cache at a lower level. But it's still useful to think of them as separate.
Inode and directory caching I'm ok with, but I'm a bit unclear on the difference between the buffer cache and page cache.
I'm also unclear how these 4 caches correspond to the 'cached' and 'buffers' columns in the output of 'free'. I would guess (from their relative size) that 'buffers' contains the inode/directrory caches, and 'cached' the page/buffer caches
Can anyone clarify please, or point me in the direction of some up to date documentation?
- Join Date
- Nov 2009
Though I can't reply clearly to your question, I'll just give you 2 links which you you may have come across already :
linux memory usage
How to use the "free" command, by The Linux Information Project (LINFO)
And if you want to pull your hair off your head :
I have in the past do much searching on this question, I did not find a clear way to understand the output. I have concluded that it's the second line, "buffer/cache", which you have not posted, that is really important. There should not be much free memory in this line.