I sometimes have the same problem with my Thinkpad X61s, running Ubuntu
Natty (2.6.38-13-generic #54-Ubuntu SMP i386 GNU/Linux). I finally found
out that the problem occurs if two conditions are met:
1. There is no LAN connection (no LAN cable is plugged in or the
LAN/router has no working Internet connection).
2. The laptop runs on mains power, not just on battery.
If both conditions are met at startup, the kworkers run amok, taking all
CPU power they can get. Since I discovered these conditions, I was able
to avoid the problem by starting the laptop from battery power when I
have no LAN. I can plug in the power cable later without problems, but
it must not be plugged in at startup or the kworkers will go crazy.
When they did, I once run "sudo perf record -ag sleep 10" and "sudo perf
report", which essentially showed the following::
53.80% kworker/0:4 [kernel.kallsyms] [k] delay_tsc
|
— delay_tsc
__const_udelay
e1000_check_phy_82574
__e1000e_read_phy_reg_igp
e1000e_write_phy_reg_m88
e1000e_phy_has_link_generic
e1000_configure_k1_ich8lan
e1000e_has_link
e1000e_up
process_one_work
worker_thread
kthread
kernel_thread_helper
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https://bugs.launchpad.net/bugs/717919
Title:
ACPI + kworker high interrupts.
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