Re: dom0 kernel profiling on Xen

[Thor Lancelot Simon <tls%panix.com@localhost>]

On Sun, Apr 03, 2016 at 07:34:25PM -0400, Thor Lancelot Simon wrote:
> Before I dig into this too much -- is this expected to work?  I'm at wits'
> end trying to track down the consumer of 50-80% "interrupt" time under I/O
> load on my dom0 elsewise.

Well, that was cool:

# kgmon -r -b
(XEN) Pagetable walk from ffffa0006050ffc8:
(XEN)  L4[0x140] = 000000120b3af027 00000000000013af
(XEN)  L3[0x001] = 00000010400fd027 000000000007fff8
(XEN)  L2[0x102] = 000000107c7d8027 0000000000011cc3 
(XEN)  L1[0x10f] = 0000000000000000 ffffffffffffffff
(XEN) domain_crash_sync called from entry.S: fault at ffff82d080215bfe create_bounce_frame+0x66/0x13a
(XEN) Domain 0 (vcpu#0) crashed on cpu#0:
(XEN) ----[ Xen-4.5.2  x86_64  debug=n  Not tainted ]----
(XEN) CPU:    0
(XEN) RIP:    e033:[<ffffffff8075f8c4>]
(XEN) RFLAGS: 0000000000010296   EM: 1   CONTEXT: pv guest (d0v0)
(XEN) rax: ffffffff813a8000   rbx: 0000000000000001   rcx: 0000000000000000
(XEN) rdx: 0000000000000004   rsi: ffffffff8020aad2   rdi: ffffffff8075f962
(XEN) rbp: ffffa00060510010   rsp: ffffa0006050ffd8   r8:  00007f8000000000
(XEN) r9:  0000000000000000   r10: ffffa00003a555a0   r11: ffffa000605100a0
(XEN) r12: ffffffff8020aad2   r13: ffffffff8075f962   r14: ffffffff80c8d020
(XEN) r15: 0000000000000004   cr0: 000000008005003b   cr4: 00000000000026f0
(XEN) cr3: 000000120b37f000   cr2: ffffa0006050ffd8
(XEN) ds: 003f   es: 003f   fs: 0000   gs: 0000   ss: e02b   cs: e033
(XEN) Guest stack trace from rsp=ffffa0006050ffd8:
(XEN)   Fault while accessing guest memory.
(XEN) Domain 0 crashed: rebooting machine in 5 seconds.