Re: 2.6.24 still causes 1000Hz wakeups on x86_64

-------- Original Message  --------
Subject: Re:2.6.24 still causes 1000Hz wakeups on x86_64
From: Jonathan Underwood <jonathan.underwood@xxxxxxxxx>
To: mike@xxxxxxxxxx, For users of Fedora <fedora-list@xxxxxxxxxx>
Date: 03/15/2008 08:21 PM

On 15/03/2008, Mike Cronenworth <mike@xxxxxxxxxx> wrote:

What's the deal? The tickless kernel shouldn't be causing wakeups at
 idle, correct?

 On a Pentium 4 3ghz HT machine, 2.6.24 shows very little wakeups
 occuring, but on my Core 2 Duo 2.1ghz machine I'm getting over 1000
 wakeups and it's keeping one core fully awake.

 powertop output:
 Top causes for wakeups:
  88.4% (1000.0)          events/0 : run_workqueue (ir_timer)
   5.5% ( 62.0)       <interrupt> : uhci_hcd:usb3, ahci, nvidia
   1.2% ( 13.2)       <interrupt> : uhci_hcd:usb4, libata
   1.1% ( 12.0)   <kernel module> : usb_hcd_poll_rh_status (rh_timer_func)
   0.9% ( 10.0)     <kernel core> : ehci_irq (ehci_watchdog)
   0.5% (  5.2)   thunderbird-bin : futex_wait (hrtimer_wakeup)

 On my P4 machine, "events/0 : run_workqueue" is further down on the list
 and isn't causing major wakeups.

 Both test machines are using Fedora 8. Latest updates. XFCE desktop. No
 process or applications are running (besides Thunderbird, obviously).
 Google searching resulted in nothing positive. Am I the only one?

On my intel core 2 duo laptop, I don't see the problem you report:

Wakeups-from-idle per second : 177.2    interval: 10.0s
no ACPI power usage estimate available

Top causes for wakeups:
  35.2% ( 58.5)      npviewer.bin : schedule_timeout (process_timeout)
  26.9% ( 44.6)      <kernel IPI> : Rescheduling interrupts
   7.8% ( 13.0)       <interrupt> : iwl3945
   5.2% (  8.6)       <interrupt> : libata
   3.8% (  6.3)       file-roller : schedule_timeout (process_timeout)
   2.8% (  4.7)                 X : do_setitimer (it_real_fn)


But you're probably seeing a legitimate bug (perhaps incorrect boot
time selection of clock source or something). It's probably worth
reporting this as a bug with as much detail about your hardware as you
can (lspci -vv etc).

Jonathan.

 Regards,
 Michael


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