On Thu, Dec 19, 2013 at 08:06:14PM +0000, Mark Brown wrote:
From: Mark Brown broonie@linaro.org
In non-heterogeneous systems like big.LITTLE systems the scheduler will be able to make better use of the available cores if we provide power numbers to it indicating their relative performance. Do this by parsing the CPU nodes in the DT.
This code currently has no effect as no information on the relative performance of the cores is provided.
Signed-off-by: Mark Brown broonie@linaro.org
arch/arm64/kernel/topology.c | 145 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 145 insertions(+)
diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
[...]
+/*
- Iterate all CPUs' descriptor in DT and compute the efficiency
- (as per table_efficiency). Also calculate a middle efficiency
- as close as possible to (max{eff_i} - min{eff_i}) / 2
- This is later used to scale the cpu_power field such that an
- 'average' CPU is of middle power. Also see the comments near
- table_efficiency[] and update_cpu_power().
- */
static void __init parse_dt_topology(void) {
- const struct cpu_efficiency *cpu_eff; struct device_node *cn;
- unsigned long min_capacity = (unsigned long)(-1);
ULONG_MAX ?
- unsigned long max_capacity = 0;
- unsigned long capacity = 0;
- int alloc_size, cpu;
- alloc_size = nr_cpu_ids * sizeof(*__cpu_capacity);
- __cpu_capacity = kzalloc(alloc_size, GFP_NOWAIT);
kcalloc ? BTW this patch should include slab.h not the previous ones, because that's the only patch where memory allocation takes place unless I am missing something.
cn = of_find_node_by_path("/cpus"); if (!cn) { @@ -158,10 +221,88 @@ static void __init parse_dt_topology(void) if (!cn) return; parse_cluster(cn);
- for_each_possible_cpu(cpu) {
const u32 *rate;int len;/* Too early to use cpu->of_node */cn = of_get_cpu_node(cpu, NULL);if (!cn) {pr_err("Missing device node for CPU %d\n", cpu);continue;}/* check if the cpu is marked as "disabled", if so ignore */if (!of_device_is_available(cn))continue;
It is time we defined what a "disabled" CPU means in ARM world, I need to have a proper look into this since this topic has been brought up before.
Lorenzo