Re: [Qemu-devel] How to measure guest memory access (qemu_ld/qemu_st) time?

[Wei-Ren Chen]

> The idea looks nice, but instead of different TLB functions selected
> at configure time, the optimization should be enabled by default.
> 
> Maybe a 'call' instruction could be used to jump to the slow path,
> that way the slow path could be shared.

  I don't understand what "maybe a 'call' instruction could be used to jump to
the slow path", could you elaborate on that? From YeongKyoon's cover letter [1],
the current flow is,

  (1) TLB check
  (2) If hit fall through, else jump to TLB miss case (5)
  (3) TLB hit case: Load value from host memory
  (4) Jump to next code (6)
  (5) TLB miss case: call MMU helper
  (6) ... (next code)

Do you mean we directly call MMU helper ing step 2?

Regards,
chenwj

[1] http://www.mail-archive.com/address@hidden/msg91294.html

-- 
Wei-Ren Chen (陳韋任)
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