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Re: cache in RAM / linux kernel



Nimrod Zimerman writes:

 > > My question -- is the parameter tunable (i.e. can I tell the kernel
 > > how much RAM to use for cache)? Where can I find it?
 > 
 > No. It was removed. The other comment you got on the list from Vadim
 > Smelyansky is, as far as I know, incorrect. It used to be tunable in
 > previous versions, but somewhere along the way all support for limiting the
 > buffer cache and swap cache sizes was removed. The proc files are still
 > there, but nothing from them is actually being used. That's true for around
 > 2.2.0pre-something, when I actually went over the sources looking for these
 > variables.

You're right -- changing these parameters made no effect. This should
probably be filed as a bug (the files are there and documented, and
yet don't do anything).

 > Can you somehow show that the new kernel is slower doing certain things than
 > less recent kernels? If we come up with a detailed report, they might
 > listen... (I would have tried 'fixing' this myself, but I really know
 > nothing about the mm sub-system, and I don't have any time to invest in
 > learning it).

I wonder how can such a thing be benchmarked?


-- 
Alex Shnitman
alexsh@hectic.net, alexsh@linux.org.il
http://alexsh.hectic.net