(Post the questions here on behalf of Yun Hsiang)
Hi all,
I’d like to ask discuss some questions about uclamp in linux-power.git<http://www.linux-arm.org/git?p=linux-power.git;a=summary>.
Code is based on the following version.
linux-power.git<http://www.linux-arm.org/git?p=linux-power.git;a=summary>
tag: topic-util_clamp-20190412
1. If a task clamped utilization is higher than a cpu capacity, should EAS bypass that cpu?
kernel/sched/fair.c
static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
{
…
/* Skip CPUs that will be overutilized. */
util = cpu_util_next(cpu, p, cpu); <= Should this util use task clamped utilization?
cpu_cap = capacity_of(cpu);
if (cpu_cap * 1024 < util * capacity_margin)
continue;
…
}
1. Will uclamp add a kernel-space API to set per-task utilization clamping?
Drivers/kernel module can use this API for precise performance/power tuning.
Best regards,
Yun
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Hi Linaro,
I am really intrested in LISA... and may I ask some question about it?
on github https://github.com/ARM-software/lisa
and PDF
https://developer.arm.com/-/media/developer/developers/open-source/energy-a…
P.43
I just read and download the source code and try to test my android phone...
however, I could not understand "Slack"'s definition in code.
===
Thus two types of test failures can result from these tests:
1. test_task_placement asserts that the placement was energy efficient. In
a big.LITTLE system, if a low-utilisation task was placed on a big CPU then
this test should be expected to fail.
*2. test_slack asserts that the required bandwidth was provided. In a
big.LITTLE system if a high-utilization task was placed on a LITTLE CPU
then this test should be expected to fail.*
===
I run generic.py and can see sometimes "Slack" is negative and sometimes is
positive...
Negative > test failed, positive > test pass...
===
How to define this SLACK + or -...? I cannot understand...
====
Besides, Could I judge my algorithm is worse or better about power
efficient by hikey_energy.py
&
est_power = self.get_power_df(experiment)
est_energy = area_under_curve(est_power.sum(axis=1), method='rect
(I don't have energy meter.... so.. I can just est by EM. Ofcause, I will
design a power for xxx_energy.py)
Really appreciate for your help.
I want to write a report and see this module is so excited.
Best,
CCC