Applying Dynamic Priority Scheduling Scheme to Static Systems of Pinwheel Task Model in Power-Aware Scheduling

Algorithm 1

A power-aware  scheduling  algorithm.

When task   𝐓_𝐢   arrived,   𝐓_𝐢   completed  and  at  deadline

 if  (ex_flag)  increase_temporal_idleness()

 else  if  (cpu  was  idle)  decrease_temporal_idleness()

 insert  𝑇_𝑖  into  TC  (at  completed)  or  delete  (at  deadline)

 recompute  TU  =  TU  ±  𝐶_𝑖/𝑃_𝑖  (when  arrived  or  at  deadline)

 last_cpu_speed  =  compute_cpu_speed (𝑇_cur)

 if  there  is  no  ready  task  to  execute  then  set  cpu  as  idle

 else  set  cpu  speed  as  last_cpu_speed

compute_cpu_speed( 𝐓_𝐣 )  //𝑇_𝑗  is  the  highest  priority  ready  task  or  null

 cpu_speed  =  CU

 for  all  tasks  𝑇_𝑖  at  TC

  if  𝑑_𝑖≤𝑑_𝑗  or  𝑇_𝑗  is  null

   cpu_speed  −=  (TI_𝑖  −  (TU_𝑖  −  CU_𝑖))

   if  cpu_speed  <  0  then  ex_flag  =  1;  break;

  else

   ex_flag  =  1;  break;

 return  (cpu_speed)  or  (0  if  cpu_speed  <  0)

decrease_temporal_idleness()

 idle_work  =  idle_period  ∗  last_cpu_speed

 for  all  tasks  𝑇_𝑖  at  TC

  if  (TI_𝑖  −  (TU_𝑖  −  CU_𝑖))  ≥  idle_work

   decrease  TI_𝑖  as  much  as  idle_work;  break;

  else

   idle_work  −=  (TI_𝑖  −  (TU_𝑖  −  CU_𝑖));  TI_𝑖  =  TU_𝑖  −  CU_𝑖;

increase_temporal_idleness()

 for  each  unused  slack  of  tasks

  distribute  unused  slack  evenly  until  deadline