Messages in this thread | | | Date | Tue, 20 Mar 2001 13:54:49 -0500 | Subject | Re: Question about memory usage in 2.4 vs 2.2 | From | Jan Harkes <> |
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On Tue, Mar 20, 2001 at 11:01:52AM -0600, Josh Grebe wrote: > Greetings, > > I have a server farm made of identical hardware running pop3 and imap mail > functions. recently, we upgraded all the machines to kernel 2.4.2, but we > noticed that according to free, our memory utilization went way up. Here > is the output of free on the 2.4.2 machine: > total used free shared buffers cached > Mem: 513192 492772 20420 0 1684 263188 > -/+ buffers/cache: 227900 285292 > Swap: 819304 540 818764 > > > On the 2.2..18 machine: > total used free shared buffers cached > Mem: 517256 351280 165976 19920 82820 186836 > -/+ buffers/cache: 81624 435632 > Swap: 819304 0 819304 > > > Doing the math, the 2.4 machine is using 44% of available memory, while > the 2.2 is using only about 14%.
What does /proc/slabinfo report for the number of pages locked down in the inode and dentry caches? My machine has pretty much every inode in memory and is using close to 50% of my memory for these (214MB/512MB).
These caches do not seem to be counted towards 'reclaimable' memory by the new VM and are only pruned when _all_ other attempts to free up memory have failed.
This becomes very noticeable on a not very fast, small memory machine (i.e. 48MB sparc-IPC), where 2.2 stays relatively snappy, but 2.4 becomes unusable after an updatedb run.
Jan
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