domU page faults under heavy network load

Kai Mosebach xen at komadev.de
Tue Feb 10 07:59:36 PST 2009


Hi,

running r188436M on Xen3.3.1 (Centos5, x86_64). The reason is not to clear but seems related to heavy load on pipes + memory + network?
It is repeatable with :

bsd8# dd if=/dev/zero | nc otherhost 12345

Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address   = 0xd216dd00
fault code              = supervisor read, page not present
instruction pointer     = 0x21:0xc02e4d40
stack pointer           = 0x29:0xc332aba8
frame pointer           = 0x29:0xc332abfc
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 1, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 12 (irq137: xn)
[thread pid 12 tid 100025 ]
Stopped at      xlvbd_add+0x2f70:       movl    0x900(%edx,%eax,4),%edx
db> bt
<console hangs>


On otherhost i get some stuff (between 19 and 62 MB), after nc closes down eventually

otherhost# nc -l 12345 | cpipe -vt -b 65535 >/dev/null 
...
thru: 108930.791ms at  184.3kB/s ( 184.3kB/s avg)   19.6MB

best Kai


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