kworker suddenly uses 55+%

[Geoffrey Leach]

kworker/0:2 suddenly started using 55+%, so I re-booted. No joy.

System is quiet.

%uname -a
Linux puget.mtranch.com 3.13.6-100.fc19.x86_64 #1 SMP Fri Mar 7 16:56:44 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

Here's the header of the perf report, which is too large for posting. I'd be happy to answer queries, of course.

# nrcpus online : 4
# nrcpus avail : 4
# cpudesc : Intel(R) Core(TM) i5-2540M CPU @ 2.60GHz
# cpuid : GenuineIntel,6,42,7
# total memory : 8081384 kB
# cmdline : /usr/bin/perf record -g -a sleep 10 
# event : name = cycles, type = 0, config = 0x0, config1 = 0x0, config2 = 0x0, excl_usr = 0, excl_kern = 0, excl_host = 0, excl_guest = 1, precise_ip = 0, attr_mmap2 = 0, attr_mmap  = 1, attr_mmap_data = 0
# HEADER_CPU_TOPOLOGY info available, use -I to display
# HEADER_NUMA_TOPOLOGY info available, use -I to display
# pmu mappings: cpu = 4, software = 1, tracepoint = 2, uncore_cbox_0 = 6, uncore_cbox_1 = 7, breakpoint = 5
# ========
#
# Samples: 53K of event 'cycles'
# Event count (approx.): 33660627666
#

suggestions? Thanks.