ondemand excessive wakeups.

ondemand excessive wakeups.

[Dave Jones]

A colleague noticed that his laptop in runlevel 3 was doing ~120 context
switches a second whilst completely idle.  Process of elimation worked out
that after disabling acpi-cpufreq & ondemand, the cs drop to around 4 per sec.

cpufreq.debug=7 yields ..

cpufreq-core: target for CPU 0: 1200000 kHz, relation 1
acpi-cpufreq: acpi_cpufreq_target 1200000 (0)
freq-table: request for target 1200000 kHz (relation: 1) for cpu 0
freq-table: target is 0 (1200000 kHz, 0)
acpi-cpufreq: get_cur_val = 100664839
cpufreq-core: notification 0 of frequency transition to 1200000 kHz
userspace: saving cpu_cur_freq of cpu 0 to be 1200000 kHz
cpufreq-core: notification 1 of frequency transition to 1200000 kHz
userspace: saving cpu_cur_freq of cpu 0 to be 1200000 kHz
cpufreq-core: target for CPU 0: 771428 kHz, relation 0
printk: 35 messages suppressed.
cpufreq-core: target for CPU 0: 1200000 kHz, relation 1
printk: 17 messages suppressed.
cpufreq-core: target for CPU 0: 1200000 kHz, relation 1
acpi-cpufreq: acpi_cpufreq_target 1200000 (0)
freq-table: request for target 1200000 kHz (relation: 1) for cpu 0
printk: 15 messages suppressed.
cpufreq-core: target for CPU 0: 1200000 kHz, relation 1
acpi-cpufreq: acpi_cpufreq_target 1200000 (0)
printk: 61 messages suppressed.
cpufreq-core: target for CPU 0: 1200000 kHz, relation 1
printk: 17 messages suppressed.
cpufreq-core: target for CPU 0: 1200000 kHz, relation 1
acpi-cpufreq: acpi_cpufreq_target 1200000 (0)

Any ideas?  With tickless now being default on i386, it's somewhat
nasty that a part of the system responsible for power saving is
causing us to waste power ;-)

	Dave

-- 
http://www.codemonkey.org.uk

RE: ondemand excessive wakeups.

[Pallipadi, Venkatesh]

>-----Original Message-----
>From: Dave Jones [mailto:davej@redhat.com] 
>Sent: Monday, March 12, 2007 12:03 PM
>To: Pallipadi, Venkatesh
>Cc: cpufreq@lists.linux.org.uk
>Subject: ondemand excessive wakeups.
>
>A colleague noticed that his laptop in runlevel 3 was doing 
>~120 context
>switches a second whilst completely idle.  Process of 
>elimation worked out
>that after disabling acpi-cpufreq & ondemand, the cs drop to 
>around 4 per sec.
>
<deleted>
>
>Any ideas?  With tickless now being default on i386, it's somewhat
>nasty that a part of the system responsible for power saving is
>causing us to waste power ;-)
>

Yes. I had previously sent a patch to eliminate this needless ondemand
polling
when system is idle.
http://lkml.org/lkml/2006/11/21/300

But, bunch of other changes in workqueue infrastructure made this patch
invalid.
I will rework this one over latest base soon.

Thanks, 
Venki

Re: ondemand excessive wakeups.

[Dave Jones]

On Mon, Mar 12, 2007 at 12:09:29PM -0700, Pallipadi, Venkatesh wrote:

 > Yes. I had previously sent a patch to eliminate this needless ondemand
 > polling
 > when system is idle.
 > http://lkml.org/lkml/2006/11/21/300

Ahh, I had completely forgotten about that thread.

 > But, bunch of other changes in workqueue infrastructure made this patch
 > invalid.
 > I will rework this one over latest base soon.

Cool, looking forward to it :)

	Dave

-- 
http://www.codemonkey.org.uk