I'm using kubuntu jaunty (i386 32bit), kernel 2.6.28-13-generic. I've 4Gb of RAM, of which only 3317Mb are seen by the system (I guess because of the 32bit system).
I'm seeing that the pagecache utilization is continually growing, up to the point that the system is unusable (after a few days). This happens also when I don't do anything (all user applications closed and the bare minimum of services enabled).
If enabled, the system starts to use swap space (using it all in the end).
Even if swap is disabled, disk activity becomes continuous, with the system unresponsive.
For example, right now the system is working (albeit a tad slow), with only Firefox and wing ide running, and I have 2Gb cached with only 45Mb mapped:
$ free total used free shared buffers cached Mem: 3346388 3247328 99060 0 8416 2117980 -/+ buffers/cache: 1120932 2225456 Swap: 2144668 519448 1625220 $ cat /proc/meminfo MemTotal: 3346388 kB MemFree: 97128 kB Buffers: 7872 kB Cached: 2120224 kB SwapCached: 413860 kB Active: 2304596 kB Inactive: 865984 kB Active(anon): 2279168 kB Inactive(anon): 830236 kB Active(file): 25428 kB Inactive(file): 35748 kB Unevictable: 32 kB Mlocked: 32 kB HighTotal: 2492940 kB HighFree: 5456 kB LowTotal: 853448 kB LowFree: 91672 kB SwapTotal: 2144668 kB SwapFree: 1625244 kB Dirty: 84 kB Writeback: 0 kB AnonPages: 629304 kB Mapped: 45768 kB Slab: 45600 kB SReclaimable: 21756 kB SUnreclaim: 23844 kB PageTables: 4468 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 3817860 kB Committed_AS: 3735020 kB VmallocTotal: 122880 kB VmallocUsed: 9352 kB VmallocChunk: 66600 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 4096 kB DirectMap4k: 16376 kB DirectMap4M: 888832 kB
If I try to drop the caches, little happens:
# sync ; echo 3 > /proc/sys/vm/drop_caches ; free total used free shared buffers cached Mem: 3346388 3220580 125808 0 3020 2100600 -/+ buffers/cache: 1116960 2229428 Swap: 2144668 519356 1625312
Right now I've vm.swappiness = 5, but I've tried also with 0 and 1 (without noticeable differences).
I've also tried vm.vfs_cache_pressure = 50 and 150 (again, no differences).
As I said the pagecache eats all memory even with swapping turned off.
What is happening? How to avoid this?