A number of memory management changes in 2.3.99-pre1 seem to wreak
havoc for me (esp. on "low-memory" systems), compared to 2.3.51.
"Problem": Qualitatively, the fraction of physical RAM allocated by the
I/O cache does NOT relinquish itself when user tasks demand memory. It
won't drop to less than about 2/3 (!!) of the total amount of physical
memory, causing merciless swapping on lower-RAM systems.
For example, simply opening 2 xterms, Netscape and GNU Emacs on a 32 MB
system causes the following situation:
total used free shared buffers cached
Mem: 30364 29584 780 0 588 19660
-/+ buffers/cache: 9336 21028
Swap: 32764 13212 19552
Only 1/3 of the memory goes to "user" memory, i.e. minus buffers and
cache. The cached RAM allocation doesn't budge, grabbing 20 MB no matter
how hard you press the system. And the machine pages itself into the
ground, seemingly unnecessarily since there's _loads_ of physical RAM
sitting in the fs cache. By comparison, 2.3.51 would free cache
pages until it was down to about 5 MB before it invoked kswapd with
any seriousness.
This new behavior appears to persist through pre2-3.
Anyone want to take a crack at this? Please? :) I'll gladly test any
suggested fixes or provide further system information off-list.
Linux syrinx 2.3.99-pre1 #4 Thu Mar 16 01:13:33 MST 2000 i586 unknown
Kernel modules 2.3.9
Gnu C egcs-2.91.66
Binutils 2.9.1.0.24
Linux C Library 2.1.2
Dynamic linker ldd (GNU libc) 2.1.2
Procps 2.0.6
Mount 2.9u
Net-tools 1.53
Console-tools 1999.03.02
Sh-utils 2.0
Modules Loaded ppp_deflate ppp_async ppp_generic slhc serial soundcore
Craig Kulesa
ckulesa@as.arizona.edu
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