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.
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
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Quoted 8 lines
-----Original Message-----
From: Dave Jones [mailto:[email protected]]
Sent: Monday, March 12, 2007 12:03 PM
To: Pallipadi, Venkatesh
Cc: [email protected]
Subject: ondemand excessive wakeups.
Quoted 7 lines
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>
Quoted 5 lines
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
Quoted 4 lines · Venkatesh
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.
Quoted 3 lines
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
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