OpenE2K/qemu-e2k
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5 Commits

Author SHA1 Message Date
Emilio G. Cota
e7e168f413 exec-all: extract tb->tc_* into a separate struct tc_tb 
In preparation for adding tc.size to be able to keep track of
TB's using the binary search tree implementation from glib.

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
 2017-10-10 07:37:10 -07:00
Emilio G. Cota
f6bb84d531 tcg: consolidate TB lookups in tb_lookup__cpu_state 
This avoids duplicating code. cpu_exec_step will also use the
new common function once we integrate parallel_cpus into tb->cflags.

Note that in this commit we also fix a race, described by Richard Henderson
during review. Think of this scenario with threads A and B:

   (A) Lookup succeeds for TB in hash without tb_lock
        (B) Sets the TB's tb->invalid flag
        (B) Removes the TB from tb_htable
        (B) Clears all CPU's tb_jmp_cache
   (A) Store TB into local tb_jmp_cache

Given that order of events, (A) will keep executing that invalid TB until
another flush of its tb_jmp_cache happens, which in theory might never happen.
We can fix this by checking the tb->invalid flag every time we look up a TB
from tb_jmp_cache, so that in the above scenario, next time we try to find
that TB in tb_jmp_cache, we won't, and will therefore be forced to look it
up in tb_htable.

Performance-wise, I measured a small improvement when booting debian-arm.
Note that inlining pays off:

 Performance counter stats for 'taskset -c 0 qemu-system-arm \
	-machine type=virt -nographic -smp 1 -m 4096 \
	-netdev user,id=unet,hostfwd=tcp::2222-:22 \
	-device virtio-net-device,netdev=unet \
	-drive file=jessie.qcow2,id=myblock,index=0,if=none \
	-device virtio-blk-device,drive=myblock \
	-kernel kernel.img -append console=ttyAMA0 root=/dev/vda1 \
	-name arm,debug-threads=on -smp 1' (10 runs):

Before:
      18714.917392 task-clock                #    0.952 CPUs utilized            ( +-  0.95% )
            23,142 context-switches          #    0.001 M/sec                    ( +-  0.50% )
                 1 CPU-migrations            #    0.000 M/sec
            10,558 page-faults               #    0.001 M/sec                    ( +-  0.95% )
    53,957,727,252 cycles                    #    2.883 GHz                      ( +-  0.91% ) [83.33%]
    24,440,599,852 stalled-cycles-frontend   #   45.30% frontend cycles idle     ( +-  1.20% ) [83.33%]
    16,495,714,424 stalled-cycles-backend    #   30.57% backend  cycles idle     ( +-  0.95% ) [66.66%]
    76,267,572,582 instructions              #    1.41  insns per cycle
                                             #    0.32  stalled cycles per insn  ( +-  0.87% ) [83.34%]
    12,692,186,323 branches                  #  678.186 M/sec                    ( +-  0.92% ) [83.35%]
       263,486,879 branch-misses             #    2.08% of all branches          ( +-  0.73% ) [83.34%]

      19.648474449 seconds time elapsed                                          ( +-  0.82% )

After, w/ inline (this patch):
      18471.376627 task-clock                #    0.955 CPUs utilized            ( +-  0.96% )
            23,048 context-switches          #    0.001 M/sec                    ( +-  0.48% )
                 1 CPU-migrations            #    0.000 M/sec
            10,708 page-faults               #    0.001 M/sec                    ( +-  0.81% )
    53,208,990,796 cycles                    #    2.881 GHz                      ( +-  0.98% ) [83.34%]
    23,941,071,673 stalled-cycles-frontend   #   44.99% frontend cycles idle     ( +-  0.95% ) [83.34%]
    16,161,773,848 stalled-cycles-backend    #   30.37% backend  cycles idle     ( +-  0.76% ) [66.67%]
    75,786,269,766 instructions              #    1.42  insns per cycle
                                             #    0.32  stalled cycles per insn  ( +-  1.24% ) [83.34%]
    12,573,617,143 branches                  #  680.708 M/sec                    ( +-  1.34% ) [83.33%]
       260,235,550 branch-misses             #    2.07% of all branches          ( +-  0.66% ) [83.33%]

      19.340502161 seconds time elapsed                                          ( +-  0.56% )

After, w/o inline:
      18791.253967 task-clock                #    0.954 CPUs utilized            ( +-  0.78% )
            23,230 context-switches          #    0.001 M/sec                    ( +-  0.42% )
                 1 CPU-migrations            #    0.000 M/sec
            10,563 page-faults               #    0.001 M/sec                    ( +-  1.27% )
    54,168,674,622 cycles                    #    2.883 GHz                      ( +-  0.80% ) [83.34%]
    24,244,712,629 stalled-cycles-frontend   #   44.76% frontend cycles idle     ( +-  1.37% ) [83.33%]
    16,288,648,572 stalled-cycles-backend    #   30.07% backend  cycles idle     ( +-  0.95% ) [66.66%]
    77,659,755,503 instructions              #    1.43  insns per cycle
                                             #    0.31  stalled cycles per insn  ( +-  0.97% ) [83.34%]
    12,922,780,045 branches                  #  687.702 M/sec                    ( +-  1.06% ) [83.34%]
       261,962,386 branch-misses             #    2.03% of all branches          ( +-  0.71% ) [83.35%]

      19.700174670 seconds time elapsed                                          ( +-  0.56% )

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
 2017-10-10 07:37:10 -07:00
Emilio G. Cota
7f11636dbe tcg: remove addr argument from lookup_tb_ptr 
It is unlikely that we will ever want to call this helper passing
an argument other than the current PC. So just remove the argument,
and use the pc we already get from cpu_get_tb_cpu_state.

This change paves the way to having a common "tb_lookup" function.

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
 2017-10-10 07:37:10 -07:00
Philippe Mathieu-Daudé
a411d29637 accel/tcg: move USER code to user-exec.c 
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20170912211934.20919-1-f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
 2017-09-17 06:52:19 -07:00
Philippe Mathieu-Daudé
61a3f8f6c0 accel/tcg: move tcg-runtime to accel/tcg/ 
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20170911213328.9701-4-f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
 2017-09-17 06:52:19 -07:00