Re: Emulate Rpi with QEMU fails

[Paul Zimmerman <pauldzim@gmail.com>]

Hi Thomas,

What does 'top' say while the emulation is running? I have an 8 cpu-thread
system, yet 'top' never shows more than about 300% cpu. I would have
thought it would get closer to 800% cpu. And running qemu as root with
nice -20 doesn't seem to make much difference.

- Paul

On Thu, Oct 8, 2020 at 12:00 AM Thomas <74cmonty@gmail.com> wrote:
>
> Interesting enough is: my top figure reported by perf is like yours:
>
> Samples: 6M of event 'cycles:u', Event count (approx.): 1936571734942
> Overhead  Command          Shared Object                  Symbol
>    7,95%  qemu-system-arm  qemu-system-arm                [.]
> helper_lookup_tb_ptr
> ◆
>    4,16%  qemu-system-arm  qemu-system-arm                [.]
> cpu_get_tb_cpu_state
> ▒
>    2,52%  qemu-system-arm  libpthread-2.32.so             [.]
> __pthread_mutex_lock
> ▒
>    2,06%  qemu-system-arm  qemu-system-arm                [.]
> qht_lookup_custom
> ▒
>    1,66%  qemu-system-arm  qemu-system-arm                [.]
> tlb_set_page_with_attrs
> ▒
>    1,61%  qemu-system-arm  libpthread-2.32.so             [.]
> __pthread_mutex_unlock_usercnt
> ▒
>    1,59%  qemu-system-arm  qemu-system-arm                [.]
> get_phys_addr
> ▒
>    1,27%  qemu-system-arm  qemu-system-arm                [.]
> cpu_exec
> ▒
>    1,23%  qemu-system-arm  qemu-system-arm                [.]
> object_class_dynamic_cast_assert
> ▒
>    0,98%  qemu-system-arm  libc-2.32.so                   [.]
> _int_malloc
> ▒
>    0,95%  qemu-system-arm  qemu-system-arm                [.]
> object_dynamic_cast_assert
> ▒
>    0,95%  qemu-system-arm  qemu-system-arm                [.]
> tb_htable_lookup
> ▒
>    0,92%  qemu-system-arm  qemu-system-arm                [.]
> tcg_gen_code
> ▒
>    0,91%  qemu-system-arm  qemu-system-arm                [.]
> qemu_mutex_lock_impl
> ▒
>    0,75%  qemu-system-arm  qemu-system-arm                [.]
> get_page_addr_code_hostp
> ▒
>    0,73%  qemu-system-arm  qemu-system-arm                [.]
> tcg_optimize
> ▒
>    0,71%  qemu-system-arm  qemu-system-arm                [.]
> qemu_mutex_unlock_impl
> ▒
>    0,69%  qemu-system-arm  libc-2.32.so                   [.]
> _int_free
> ▒
>    0,64%  qemu-system-arm  qemu-system-arm                [.]
> tb_flush_jmp_cache
> ▒
>    0,63%  qemu-system-arm  qemu-system-arm                [.]
> address_space_ldl_le
> ▒
>    0,62%  qemu-system-arm  libpthread-2.32.so             [.]
> __lll_lock_wait
> ▒
>    0,58%  qemu-system-arm  libpthread-2.32.so             [.]
> pthread_cond_wait@@GLIBC_2.3.2
> ▒
>    0,52%  qemu-system-arm  qemu-system-arm                [.]
> cpu_reset_interrupt
> ▒
>    0,52%  qemu-system-arm  libc-2.32.so                   [.]
> cfree@GLIBC_2.2.5
> ▒
>    0,52%  qemu-system-arm  qemu-system-arm                [.]
> qemu_set_irq
> ▒
>
> However the absolute time is 3-4 minutes.
> And I don't know where I should start optimization now.
>
>
>
> Am 07.10.20 um 14:02 schrieb Alex Bennée:
> > Thomas Schneider <74cmonty@gmail.com> writes:
> >
> >> Are you referring to this tool?
> >> https://github.com/stefano-garzarella/qemu-boot-time
> >> <https://github.com/stefano-garzarella/qemu-boot-time>
> > No - just plain perf:
> >
> >   perf record $QEMU $ARGS
> >
> > Then a "perf report" which will show you the hotspots, for example:
> >
> >    8.92%  qemu-system-aar  qemu-system-aarch64      [.] helper_lookup_tb_ptr
> >    4.76%  qemu-system-aar  qemu-system-aarch64      [.] liveness_pass_1
> >    3.69%  qemu-system-aar  qemu-system-aarch64      [.] tcg_gen_code
> >    2.95%  qemu-system-aar  qemu-system-aarch64      [.] qht_lookup_custom
> >    2.93%  qemu-system-aar  qemu-system-aarch64      [.] tcg_optimize
> >    1.28%  qemu-system-aar  qemu-system-aarch64      [.] tcg_out_opc.isra.15
> >    1.09%  qemu-system-aar  qemu-system-aarch64      [.] get_phys_addr_lpae
> >    1.09%  qemu-system-aar  [kernel.kallsyms]        [k] isolate_freepages_block
> >    1.05%  qemu-system-aar  qemu-system-aarch64      [.] cpu_get_tb_cpu_state
> >    0.98%  qemu-system-aar  [kernel.kallsyms]        [k] do_syscall_64
> >    0.94%  qemu-system-aar  qemu-system-aarch64      [.] tb_lookup_cmp
> >    0.78%  qemu-system-aar  qemu-system-aarch64      [.] init_ts_info
> >    0.73%  qemu-system-aar  qemu-system-aarch64      [.] tb_htable_lookup
> >    0.73%  qemu-system-aar  qemu-system-aarch64      [.] tb_gen_code
> >    0.73%  qemu-system-aar  qemu-system-aarch64      [.] tlb_set_page_with_attrs
> >
> >>
> >> Am 07.10.2020 um 13:00 schrieb Alex Bennée:
> >>> perf to record your boot
> >
>