[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Xen-devel] Whats effect of EXTRA_MEM_RATIO



Hi guys,

Im fairly new to the Xen Development & trying to understand ballooning.

While compiling a DomU kernel I'm trying to understand the e820 memory map w.r.t Xen,

I have modified arch/x86/xen/setup.c  EXTRA_MEM_RATIO  to 1 and can see that the guest can not balloon up more than 2GB. Below is the memory map of DomU with max mem as 16GB.

for EXTRA_MEM_RATIO  = 1

BIOS-provided physical RAM map:
 Xen: 0000000000000000 - 00000000000a0000 (usable)
 Xen: 00000000000a0000 - 0000000000100000 (reserved)
 Xen: 0000000000100000 - 0000000080000000 (usable)
 Xen: 0000000080000000 - 0000000400000000 (unusable)
NX (Execute Disable) protection: active
DMI not present or invalid.
e820 update range: 0000000000000000 - 0000000000010000 (usable) ==> (reserved)
e820 remove range: 00000000000a0000 - 0000000000100000 (usable)
No AGP bridge found
last_pfn = 0x80000 max_arch_pfn = 0x400000000
initial memory mapped : 0 - 0436c000
Base memory trampoline at [ffff88000009b000] 9b000 size 20480
init_memory_mapping: 0000000000000000-0000000080000000
 0000000000 - 0080000000 page 4k
kernel direct mapping tables up to 80000000 @ bfd000-1000000
xen: setting RW the range fd6000 - 1000000


for EXTRA_MEM_RATIO  = 10 the map is like below and can balloon up to 16GB.

BIOS-provided physical RAM map:
 Xen: 0000000000000000 - 00000000000a0000 (usable)
 Xen: 00000000000a0000 - 0000000000100000 (reserved)
 Xen: 0000000000100000 - 0000000400000000 (usable)
NX (Execute Disable) protection: active
DMI not present or invalid.
e820 update range: 0000000000000000 - 0000000000010000 (usable) ==> (reserved)
e820 remove range: 00000000000a0000 - 0000000000100000 (usable)
No AGP bridge found
last_pfn = 0x400000 max_arch_pfn = 0x400000000
last_pfn = 0x100000 max_arch_pfn = 0x400000000
initial memory mapped : 0 - 0436c000
Base memory trampoline at [ffff88000009b000] 9b000 size 20480
init_memory_mapping: 0000000000000000-0000000100000000
 0000000000 - 0100000000 page 4k
kernel direct mapping tables up to 100000000 @ 7fb000-1000000
xen: setting RW the range fd6000 - 1000000
init_memory_mapping: 0000000100000000-0000000400000000
 0100000000 - 0400000000 page 4k
kernel direct mapping tables up to 400000000 @ 601ef000-62200000
xen: setting RW the range 619fb000 - 62200000



Can someone please help me understand its behavior and importance ?

Thanks.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel

 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.