lkml.org 
[lkml]   [2020]   [Jan]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v1] arch_topology: Adjust initial CPU capacities with current freq
From
Date
On 10/01/2020 12:37, Sudeep Holla wrote:
> On Thu, Jan 09, 2020 at 03:52:14PM +0800, Jeffy Chen wrote:
>> The CPU freqs are not supposed to change before cpufreq policies
>> properly registered, meaning that they should be used to calculate the
>> initial CPU capacities.
>>
>> Doing this helps choosing the best CPU during early boot, especially
>> for the initramfs decompressing.
>>
>> Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
>
> [...]
>
>> @@ -146,10 +153,15 @@ bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
>> return false;
>> }
>> }
>> - capacity_scale = max(cpu_capacity, capacity_scale);
>> raw_capacity[cpu] = cpu_capacity;
>> pr_debug("cpu_capacity: %pOF cpu_capacity=%u (raw)\n",
>> cpu_node, raw_capacity[cpu]);
>> +
>> + cpu_clk = of_clk_get(cpu_node, 0);
>> + if (!PTR_ERR_OR_ZERO(cpu_clk))
>> + per_cpu(max_freq, cpu) = clk_get_rate(cpu_clk) / 1000;
>> +
>> + clk_put(cpu_clk);
>
> I don't like to assume DVFS to be supplied only using 'clk'. So NACK!
> We have other non-clk mechanism for CPU DVFS and this needs to simply
> use cpufreq APIs to get frequency value if required.

To support this, it's failing on my Arm64 Juno board.

...
[ 0.084858] CPU1 cpu_clk=-517
[ 0.087961] CPU2 cpu_clk=-517
[ 0.091005] CPU0 cpu_clk=-517
[ 0.094121] CPU3 cpu_clk=-517
[ 0.097248] CPU4 cpu_clk=-517
[ 0.100415] CPU5 cpu_clk=-517
...

Since you're on a big.LITTLE platform, did you specify
'capacity-dmips-mhz' for CPUs to be able to distinguish big and little
CPUs before CPUfreq kicks in?

$ grep capacity-dmips-mhz ./arch/arm64/boot/dts/arm/juno.dts
capacity-dmips-mhz = <1024>;
capacity-dmips-mhz = <1024>;
capacity-dmips-mhz = <578>;
capacity-dmips-mhz = <578>;
capacity-dmips-mhz = <578>;
capacity-dmips-mhz = <578>;

\
 
 \ /
  Last update: 2020-01-10 13:01    [W:0.084 / U:2.256 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site