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Date: Tue, 22 May 2012 10:38:33 +0800
From: =?utf-8?B?6Zmz6Z+L5Lu7?= <chenwj@iis.sinica.edu.tw>
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Subject: Re: [Qemu-devel] Is it possible to retrieve pre-process information
 in QEMU?
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To: Mulyadi Santosa <mulyadi.santosa@gmail.com>
Cc: qemu-devel@nongnu.org, =?utf-8?B?6Zmz6Z+L5Lu7?= <chenwj@iis.sinica.edu.tw>

> > =C2=A0I would like to know if I can retrieve pre-process information =
in QEMU
> > system mode. For example, I want to know each process's page fault ra=
tio.
> > Is there a way to do that?
>=20
> logically, it's possible, but you need to locate the task_struct of
> each processes first. Using GDB, that might be a bit easier but still
> not easy.
>=20
> Why not just monitor it inside the guest? using system tap for example?

  O.K., what I did is something like below,

---
void tlb_fill(CPUARMState *env1, target_ulong addr, int is_write, int mmu=
_idx,
              uintptr_t retaddr)
{
    ret =3D cpu_arm_handle_mmu_fault(env, addr, is_write, mmu_idx);
    if (unlikely(ret)) {
        page_fault++;   // page fault
    }
    env =3D saved_env;
}
---

  IIUC, cpu_arm_handle_mmu_fault will lookup guest page table, return 1 i=
f there
is a page fault, that's why I add a counter there. But this way I'll coll=
ect a
global static not per-process one. I'll try systemtap latter but not sure=
 it
does the same thing I want to do.

  Any thoughts? :)

Regards,
chenwj

--=20
Wei-Ren Chen (=E9=99=B3=E9=9F=8B=E4=BB=BB)
Computer Systems Lab, Institute of Information Science,
Academia Sinica, Taiwan (R.O.C.)
Tel:886-2-2788-3799 #1667
Homepage: http://people.cs.nctu.edu.tw/~chenwj