On Wed, 26 Mar 2008 22:57:57 -0700
Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
Ah, I see what it is. I wasn't trying to add enough memory. It adds in units of SECTION_SIZE_BITS, which is 2^30 on 32-bit PAE. When I increase the initial balloon extension to PAGES_PER_SECTION pages, I make some more progress:At first, I believe usual DIMM size is bigger than SECTION_SIZE_BITS. This is
xen_balloon: Initialising balloon driver.
trying to reserve 262144 pages (1073741824 bytes) for balloon
bootmem alloc of 147456 bytes failed!
Kernel panic - not syncing: Out of memory
Pid: 1, comm: swapper Not tainted 2.6.25-rc7-x86-latest.git-dirty #361
[<c01299dc>] panic+0x49/0x102
[<c0647c3c>] __alloc_bootmem+0x24/0x29
[<c0647c6d>] __alloc_bootmem_node+0x2c/0x34
[<c044bd97>] zone_wait_table_init+0x45/0x95
[<c0467258>] init_currently_empty_zone+0x1d/0xaa
[<c01738ea>] __add_pages+0x88/0xdb
[<c011c1a5>] arch_add_memory+0x25/0x2b
[<c01737a9>] add_memory_resource+0x2f/0x36
[<c064e487>] balloon_init+0x1b8/0x2b9
[<c0635495>] kernel_init+0x137/0x292
[<c063535e>] ? kernel_init+0x0/0x292
[<c063535e>] ? kernel_init+0x0/0x292
[<c0108b67>] kernel_thread_helper+0x7/0x10
=======================
What's the rationale for setting SECTION_SIZE_BITS to 30? Seems like a fairly large chunk.
designed for hardware-based hotplug.
If you want to use memory-hotplug for virtualized enviroment, it's good to make
this to be smaller chunk. Powerpc/IBM lpar uses 16MB chunk.
It's a trade-off between section mainainance cost v.s. size of plugged memory.
please find the best.