Re: [Qemu-devel] [PATCH v4 0/7] Measure Tiny Code Generation Quality

[Alex Bennée]

vandersonmr <address@hidden> writes:

> This patch is part of Google Summer of Code (GSoC) 2019.
> More about the project can be found in:
> https://wiki.qemu.org/Internships/ProjectIdeas/TCGCodeQuality
>
> The goal of this patch is to add infrastructure to collect
> execution and JIT statistics during the emulation with accel/TCG.
> The statistics are stored in TBStatistic structures (TBStats)
> with each TB having its respective TBStats.
>
> We added -d tb_stats and HMP tb_stats commands to allow the control
> of this statistics collection. And info tb, tbs, and coverset commands
> were also added to allow dumping and exploring all this information
> while emulating.

Hmm with:

  -d tb_stats:10:all

I'm seeing the following bt:

  Thread 4 "qemu-system-aar" received signal SIGABRT, Aborted.
  [Switching to Thread 0x7fffe5285700 (LWP 898)]
  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
  50      ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
  (gdb) bt
  #0  0x00007ffff51787bb in __GI_raise (sig=sig@entry=6) at 
../sysdeps/unix/sysv/linux/raise.c:50
  #1  0x00007ffff5163535 in __GI_abort () at abort.c:79
  #2  0x0000555555bab663 in OP_E (bytemode=2, sizeflag=3) at 
/home/alex/lsrc/qemu.git/disas/i386.c:5094
  #3  0x0000555555ba972f in print_insn (pc=140735911299712, 
info=0x7fffe5281c00) at /home/alex/lsrc/qemu.git/disas/i386.c:4071
  #4  0x0000555555ba8623 in print_insn_i386 (pc=140735911299712, 
info=0x7fffe5281c00) at /home/alex/lsrc/qemu.git/disas/i386.c:3705
  #5  0x0000555555881241 in get_num_insts (code=0x7fffa2000a80 
<code_gen_buffer+33557075>, size=88) at /home/alex/lsrc/qemu.git/disas.c:575
  #6  0x00005555558d89f1 in tb_gen_code (cpu=0x555556a1f6a0, 
pc=18446743524230025728, cs_base=0, flags=2415924229, cflags=-16252928) at 
/home/alex/lsrc/qemu.git/accel/tcg/translate-all.c:1881
  #7  0x00005555558d4984 in tb_find (cpu=0x555556a1f6a0, last_tb=0x0, 
tb_exit=0, cf_mask=524288) at /home/alex/lsrc/qemu.git/accel/tcg/cpu-exec.c:409
  #8  0x00005555558d524f in cpu_exec (cpu=0x555556a1f6a0) at 
/home/alex/lsrc/qemu.git/accel/tcg/cpu-exec.c:731
  #9  0x0000555555884806 in tcg_cpu_exec (cpu=0x555556a1f6a0) at 
/home/alex/lsrc/qemu.git/cpus.c:1435
  #10 0x000055555588505c in qemu_tcg_cpu_thread_fn (arg=0x555556a1f6a0) at 
/home/alex/lsrc/qemu.git/cpus.c:1743
  #11 0x0000555556010875 in qemu_thread_start (args=0x555556a75450) at 
/home/alex/lsrc/qemu.git/util/qemu-thread-posix.c:502
  #12 0x00007ffff530bfa3 in start_thread (arg=<optimized out>) at 
pthread_create.c:486
  #13 0x00007ffff523a4cf in clone () at 
../sysdeps/unix/sysv/linux/x86_64/clone.S:95


>
> Collecting these statistics and information is useful to understand
> qemu performance and to help to add the support for traces to QEMU.
>
> vandersonmr (7):
>   accel: introducing TBStatistics structure
>   accel: collecting TB execution count
>   accel: collecting JIT statistics
>   accel: replacing part of CONFIG_PROFILER with TBStats
>   log: adding -d tb_stats to control tbstats
>   monitor: adding tb_stats hmp command
>   monitor: adding info tbs, tb, and coverset
>
>  accel/tcg/Makefile.objs      |   2 +-
>  accel/tcg/tb-stats.c         | 489 +++++++++++++++++++++++++++++++++++
>  accel/tcg/tcg-runtime.c      |   7 +
>  accel/tcg/tcg-runtime.h      |   2 +
>  accel/tcg/translate-all.c    |  93 ++++++-
>  accel/tcg/translator.c       |   6 +
>  disas.c                      | 108 ++++++++
>  hmp-commands-info.hx         |  23 ++
>  hmp-commands.hx              |  17 ++
>  include/disas/disas.h        |   1 +
>  include/exec/exec-all.h      |  15 +-
>  include/exec/gen-icount.h    |   9 +
>  include/exec/tb-context.h    |  12 +
>  include/exec/tb-hash.h       |   7 +
>  include/exec/tb-stats.h      | 113 ++++++++
>  include/qemu/log-for-trace.h |   2 +
>  include/qemu/log.h           |  16 ++
>  linux-user/exit.c            |   4 +
>  monitor/misc.c               | 111 ++++++++
>  tcg/tcg.c                    | 114 +++-----
>  tcg/tcg.h                    |  12 +-
>  util/log.c                   |  99 ++++++-
>  22 files changed, 1144 insertions(+), 118 deletions(-)
>  create mode 100644 accel/tcg/tb-stats.c
>  create mode 100644 include/exec/tb-stats.h


--
Alex Bennée