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semperfiguy

Member

Registered: 2007-12-03

Posts: 224

Powertop and 50% of wakeups

I recently started using powertop to see if I could get some extra battery life. One of the first suggestions it makes is:

Suggestion: Enable SATA ALPM link power management via:
  echo min_power > /sys/class/scsi_host/host0/link_power_management_policy

Is this safe enough to place into rc.local? It won't harm my hard drive in any way over the long run? Also, Powertop is reporting that 50-67% of wakeups come from extra timer interrupt. Is there any way to stop those interrupts from happening? How much do they even affect my battery?

Here is powertop output:

Wakeups-from-idle per second : 197.7    interval: 3.0s                                                   
Power usage (5 minute ACPI estimate) :  21.5 W (1.6 hours left)

Top causes for wakeups:
  68.3% (262.3)       <interrupt> : extra timer interrupt 
   9.0% ( 34.7)       <interrupt> : PS/2 keyboard/mouse/touchpad 
   5.1% ( 19.7)           firefox : hrtimer_start_range_ns (hrtimer_wakeup) 
   3.5% ( 13.3)       <interrupt> : ath 
   2.9% ( 11.0)       wicd-client : hrtimer_start_range_ns (hrtimer_wakeup) 
   2.5% (  9.7)         xbindkeys : hrtimer_start_range_ns (hrtimer_wakeup)
   1.6% (  6.0)       <interrupt> : ide0
   0.9% (  3.3)             conky : hrtimer_start_range_ns (hrtimer_wakeup)
   0.8% (  3.0)               mpd : sk_reset_timer (tcp_write_timer)
   0.5% (  2.0)             ncmpc : hrtimer_start_range_ns (hrtimer_wakeup)
   0.5% (  2.0)             ncmpc : sk_reset_timer (tcp_delack_timer)
   0.5% (  2.0)             conky : sk_reset_timer (tcp_delack_timer)
   0.5% (  2.0)             ncmpc : sk_reset_timer (tcp_write_timer)
   0.4% (  1.7)     <kernel core> : blk_plug_device (blk_unplug_timeout)
   0.3% (  1.3)             irssi : hrtimer_start_range_ns (hrtimer_wakeup)
   0.3% (  1.0)       <interrupt> : nvidia
   0.3% (  1.0)      <kernel IPI> : Rescheduling interrupts
   0.3% (  1.0)             conky : sk_reset_timer (tcp_write_timer)
   0.3% (  1.0)                 X : nv_start_rc_timer (nv_kern_rc_timer)
   0.2% (  0.7)              curl : hrtimer_start_range_ns (hrtimer_wakeup)
   0.2% (  0.7)              htop : hrtimer_start_range_ns (hrtimer_wakeup)
   0.1% (  0.3)      <kernel IPI> : TLB shootdowns
   0.1% (  0.3)             urxvt : sys_epoll_wait (process_timeout)
   0.1% (  0.3)            thunar : hrtimer_start_range_ns (hrtimer_wakeup)
   0.1% (  0.3)                 X : hrtimer_start_range_ns (hrtimer_wakeup)
   0.1% (  0.3)     <kernel core> : enqueue_task_rt (sched_rt_period_timer)
   0.1% (  0.3)              curl : sk_reset_timer (tcp_write_timer)

Suggestion: Enable SATA ALPM link power management via:
  echo min_power > /sys/class/scsi_host/host0/link_power_management_policy
or press the S key.