Re: [Qemu-devel] [PATCH v2 43/45] tcg: introduce regions to split code_gen_buffer

[Emilio G. Cota]

On Mon, Jul 17, 2017 at 19:09:28 -1000, Richard Henderson wrote:
> On 07/16/2017 10:04 AM, Emilio G. Cota wrote:
> >+#ifdef CONFIG_SOFTMMU
> >+/*
> >+ * It is likely that some vCPUs will translate more code than others, so we
> >+ * first try to set more regions than smp_cpus, with those regions being
> >+ * larger than the minimum code_gen_buffer size. If that's not possible we
> >+ * make do by evenly dividing the code_gen_buffer among the vCPUs.
> >+ */
> >+void softmmu_tcg_region_init(void)
> >+{
> >+    size_t i;
> >+
> >+    /* Use a single region if all we have is one vCPU thread */
> >+    if (smp_cpus == 1 || !qemu_tcg_mttcg_enabled()) {
> >+        tcg_region_init(0);
> >+        return;
> >+    }
> >+
> >+    for (i = 8; i > 0; i--) {
> >+        size_t regions_per_thread = i;
> >+        size_t region_size;
> >+
> >+        region_size = tcg_init_ctx.code_gen_buffer_size;
> >+        region_size /= smp_cpus * regions_per_thread;
> >+
> >+        if (region_size >= 2 * MIN_CODE_GEN_BUFFER_SIZE) {
> >+            tcg_region_init(smp_cpus * regions_per_thread);
> >+            return;
> >+        }
> >+    }
> >+    tcg_region_init(smp_cpus);
> >+}
> >+#endif
> 
> Any reason this code wouldn't just live in tcg_region_init?
> It would certainly simplify the interface.

Good point. Will move it there, adding a comment to make sure the
function is called once qemu_tcg_mttcg_enabled() has been set up.

                E.