Dear Dave, >> Seems that any i386 PAE machine will go OOM just by running a few >> processes. To reproduce: >> sh -c 'n=0; while [ $n -lt 19999 ]; do sleep 600 & ((n=n+1)); done' >> ... > I think what you're seeing here is that, as the amount of total memory > increases, the amount of lowmem available _decreases_ due to inflation > of mem_map[] (and a few other more minor things). The number of sleeps > you can do is bound by the number of processes, as you noticed from > ulimit. Creating processes that don't use much memory eats a relatively > large amount of low memory. > This is a sad (and counterintuitive) fact: more RAM actually *CREATES* > RAM bottlenecks on 32-bit systems. I understand that more RAM leaves less lowmem. What is unacceptable is that PAE crashes or freezes with OOM: it should gracefully handle the issue. Noting that (for a machine with 4GB or under) PAE fails where the HIGHMEM4G kernel succeeds and survives. >> On my large machine, 'free' fails to show about 2GB memory ... > You probably have a memory hole. ... > The e820 map (during early boot in dmesg) or /proc/iomem will let you > locate your memory holes. Thanks, that might explain it. Output of /proc/iomem below: sorry I do not know how to interpret it. Cheers, Paul Paul Szabo psz@xxxxxxxxxxxxxxxxx http://www.maths.usyd.edu.au/u/psz/ School of Mathematics and Statistics University of Sydney Australia --- root@zeno:~# cat /proc/iomem 00000000-0000ffff : reserved 00010000-00099bff : System RAM 00099c00-0009ffff : reserved 000a0000-000bffff : PCI Bus 0000:00 000a0000-000bffff : Video RAM area 000c0000-000dffff : PCI Bus 0000:00 000c0000-000c7fff : Video ROM 000c8000-000cf5ff : Adapter ROM 000cf800-000d07ff : Adapter ROM 000d0800-000d0bff : Adapter ROM 000e0000-000fffff : reserved 000f0000-000fffff : System ROM 00100000-7e445fff : System RAM 01000000-01610e15 : Kernel code 01610e16-01802dff : Kernel data 01880000-018b2fff : Kernel bss 7e446000-7e565fff : ACPI Non-volatile Storage 7e566000-7f1e2fff : reserved 7f1e3000-7f25efff : ACPI Tables 7f25f000-7f31cfff : reserved 7f31d000-7f323fff : ACPI Non-volatile Storage 7f324000-7f333fff : reserved 7f334000-7f33bfff : ACPI Non-volatile Storage 7f33c000-7f365fff : reserved 7f366000-7f7fffff : ACPI Non-volatile Storage 7f800000-7fffffff : RAM buffer 80000000-dfffffff : PCI Bus 0000:00 80000000-8fffffff : PCI MMCONFIG 0000 [bus 00-ff] 80000000-8fffffff : reserved 90000000-9000000f : 0000:00:16.0 90000010-9000001f : 0000:00:16.1 dd000000-ddffffff : PCI Bus 0000:08 dd000000-ddffffff : 0000:08:03.0 de000000-de4fffff : PCI Bus 0000:07 de000000-de3fffff : 0000:07:00.0 de47c000-de47ffff : 0000:07:00.0 de600000-de6fffff : PCI Bus 0000:02 df000000-df8fffff : PCI Bus 0000:08 df000000-df7fffff : 0000:08:03.0 df800000-df803fff : 0000:08:03.0 df900000-df9fffff : PCI Bus 0000:07 dfa00000-dfafffff : PCI Bus 0000:02 dfa00000-dfa1ffff : 0000:02:00.1 dfa00000-dfa1ffff : igb dfa20000-dfa3ffff : 0000:02:00.0 dfa20000-dfa3ffff : igb dfa40000-dfa43fff : 0000:02:00.1 dfa40000-dfa43fff : igb dfa44000-dfa47fff : 0000:02:00.0 dfa44000-dfa47fff : igb dfb00000-dfb03fff : 0000:00:04.7 dfb04000-dfb07fff : 0000:00:04.6 dfb08000-dfb0bfff : 0000:00:04.5 dfb0c000-dfb0ffff : 0000:00:04.4 dfb10000-dfb13fff : 0000:00:04.3 dfb14000-dfb17fff : 0000:00:04.2 dfb18000-dfb1bfff : 0000:00:04.1 dfb1c000-dfb1ffff : 0000:00:04.0 dfb20000-dfb200ff : 0000:00:1f.3 dfb21000-dfb217ff : 0000:00:1f.2 dfb21000-dfb217ff : ahci dfb22000-dfb223ff : 0000:00:1d.0 dfb22000-dfb223ff : ehci_hcd dfb23000-dfb233ff : 0000:00:1a.0 dfb23000-dfb233ff : ehci_hcd dfb25000-dfb25fff : 0000:00:05.4 dfffc000-dfffdfff : pnp 00:02 e0000000-fbffffff : PCI Bus 0000:80 fbe00000-fbefffff : PCI Bus 0000:84 fbe00000-fbe3ffff : 0000:84:00.0 fbe40000-fbe5ffff : 0000:84:00.0 fbe60000-fbe63fff : 0000:84:00.0 fbf00000-fbf03fff : 0000:80:04.7 fbf04000-fbf07fff : 0000:80:04.6 fbf08000-fbf0bfff : 0000:80:04.5 fbf0c000-fbf0ffff : 0000:80:04.4 fbf10000-fbf13fff : 0000:80:04.3 fbf14000-fbf17fff : 0000:80:04.2 fbf18000-fbf1bfff : 0000:80:04.1 fbf1c000-fbf1ffff : 0000:80:04.0 fbf20000-fbf20fff : 0000:80:05.4 fbffe000-fbffffff : pnp 00:12 fc000000-fcffffff : pnp 00:01 fd000000-fdffffff : pnp 00:01 fe000000-feafffff : pnp 00:01 feb00000-febfffff : pnp 00:01 fec00000-fec003ff : IOAPIC 0 fec01000-fec013ff : IOAPIC 1 fec40000-fec403ff : IOAPIC 2 fed00000-fed003ff : HPET 0 fed08000-fed08fff : pnp 00:0c fed1c000-fed3ffff : reserved fed1c000-fed1ffff : pnp 00:0c fed45000-fedfffff : pnp 00:01 fee00000-fee00fff : Local APIC ff000000-ffffffff : reserved ff000000-ffffffff : pnp 00:0c 100000000-107fffffff : System RAM root@zeno:~# -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>