I have a couple of servers with 20-30 GB RAM that are running (a variant of) RHEL4. They are currently running the SMP i386 kernel, not x64, not even the hugemem kernel. This means LowMem is confined to < 1G, and thus dentry_cache and ext3_inode_cache to 100M or so each. How can I tell if this is a problem?

Here's a typical vmstat report while it's compiling some Java:

$ vmstat 10
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa
 1  1      0 19493816 394740 922420    0    0  1058 2292 1491 1020  6  3 80 12
 2  1      0 19519480 395244 850156    0    0  1179 1412 1329 1195  9  4 75 12
 1  1      0 19557368 392616 828344    0    0  1783 1680 1498 1756 14  5 72  9

I don't like the way bi is nonzero when there is so much memory free. I imagine slabtop could point more directly to the problem but I don't really understand how to interpret its output.