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tcg: round-robin: do not use mb_read for rr_current_cpu 

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2023-03-03 13:18:23 +01:00
parent 856e23a0fb
commit 2e73952926
1 changed files with 7 additions and 4 deletions
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11
accel/tcg/tcg-accel-ops-rr.c
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@ -72,11 +72,13 @@ static void rr_kick_next_cpu(void)
{ {
CPUState *cpu; CPUState *cpu;
do { do {
cpu = qatomic_mb_read(&rr_current_cpu); cpu = qatomic_read(&rr_current_cpu);
if (cpu) { if (cpu) {
cpu_exit(cpu); cpu_exit(cpu);
} }
} while (cpu != qatomic_mb_read(&rr_current_cpu)); /* Finish kicking this cpu before reading again. */
smp_mb();
} while (cpu != qatomic_read(&rr_current_cpu));
} }
static void rr_kick_thread(void *opaque) static void rr_kick_thread(void *opaque)
@ -241,8 +243,9 @@ static void *rr_cpu_thread_fn(void *arg)
} }
while (cpu && cpu_work_list_empty(cpu) && !cpu->exit_request) { while (cpu && cpu_work_list_empty(cpu) && !cpu->exit_request) {
/* Store rr_current_cpu before evaluating cpu_can_run(). */
qatomic_mb_set(&rr_current_cpu, cpu); qatomic_mb_set(&rr_current_cpu, cpu);
current_cpu = cpu; current_cpu = cpu;
qemu_clock_enable(QEMU_CLOCK_VIRTUAL, qemu_clock_enable(QEMU_CLOCK_VIRTUAL,
@ -280,7 +283,7 @@ static void *rr_cpu_thread_fn(void *arg)
cpu = CPU_NEXT(cpu); cpu = CPU_NEXT(cpu);
} /* while (cpu && !cpu->exit_request).. */ } /* while (cpu && !cpu->exit_request).. */
/* Does not need qatomic_mb_set because a spurious wakeup is okay. */ /* Does not need a memory barrier because a spurious wakeup is okay. */
qatomic_set(&rr_current_cpu, NULL); qatomic_set(&rr_current_cpu, NULL);
if (cpu && cpu->exit_request) { if (cpu && cpu->exit_request) {