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From: | Philippe Mathieu-Daudé |
Subject: | Re: [PATCH 1/3] softmmu/cpus: Only set parallel_cpus for SMP |
Date: | Mon, 31 Aug 2020 19:17:13 +0200 |
Do not set parallel_cpus if there is only one cpu instantiated.
This will allow tcg to use serial code to implement atomics.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
softmmu/cpus.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/softmmu/cpus.c b/softmmu/cpus.c
index a802e899ab..e3b98065c9 100644
--- a/softmmu/cpus.c
+++ b/softmmu/cpus.c
@@ -1895,6 +1895,16 @@ static void qemu_tcg_init_vcpu(CPUState *cpu)
if (!tcg_region_inited) {
tcg_region_inited = 1;
tcg_region_init();
+ /*
+ * If MTTCG, and we will create multiple cpus,
+ * then we will have cpus running in parallel.
+ */
+ if (qemu_tcg_mttcg_enabled()) {
+ MachineState *ms = MACHINE(qdev_get_machine());
+ if (ms->smp.max_cpus > 1) {
+ parallel_cpus = true;
+ }
+ }
}
if (qemu_tcg_mttcg_enabled() || !single_tcg_cpu_thread) {
@@ -1904,7 +1914,6 @@ static void qemu_tcg_init_vcpu(CPUState *cpu)
if (qemu_tcg_mttcg_enabled()) {
/* create a thread per vCPU with TCG (MTTCG) */
- parallel_cpus = true;
snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/TCG",
cpu->cpu_index);
--
2.25.1
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