X86_64: Many Lost ticks

[kernel-stuff]

I have a X86_64 laptop (Compaq Presario R3240) with all BIOS updates in place. I routinely get the "Warning : many lost ticks" message in dmesg. 

I booted with report_lost_ticks after seeing the source of arch/x86_86/kernel/time.c:handle_lost_ticks and it reported that rip was at acpi_ec_read most of the times.

Why is this warning caused and what's the effect? In handle_lost_ticks, it does not seem to compensate for the lost ticks..

Parry. 

dmesg with report_lost_ticks=1
========================================================
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
ip_tables: (C) 2000-2002 Netfilter core team
ip_tables: (C) 2000-2002 Netfilter core team
eth0: link up, 10Mbps, half-duplex, lpa 0x0000
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
i2c /dev entries driver
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 3 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
eth0: no IPv6 routers present
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
input: PS/2 Generic Mouse on isa0060/serio4
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 2 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 2 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 2 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 4 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 4 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 4 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 2 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 2 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 2 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
warning: many lost ticks.
Your time source seems to be instable or some driver is hogging interupts
rip __do_softirq+0x41/0xa2
time.c: Lost 1 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 5 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 2 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 4 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
time.c: Lost 5 timer tick(s)! rip acpi_ec_read+0xce/0xed)
time.c: Lost 1 timer tick(s)! rip __do_softirq+0x41/0xa2)
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