How to tell if PAE is hurting me?
- by James
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.