Re: [BISECTED] 2.6.35.*: horrible (exponential? >linear) slowdownto unusability (HPET)

From: Artur Skawina
Date: Tue Sep 14 2010 - 18:23:32 EST


> On 14 Sep 2010, Thomas Gleixner said:
>> Another question. If you add hpet=verbose (or revert that commit) does
>> the printk_once in hpet_set_next_event() show up in dmesg ?
>>
>> "hpet: compare register read back failed."

Since adding back that extra read, the box here, which previously
was showing the symptoms every couple of days, has been ok; so i'm
now ~80% sure this change was indeed the cause. Nothing new in logs.

$ dmesg | grep -i hpet
ACPI: HPET 00000000bfee5dc0 00038 (v01 GBT GBTUACPI 42302E31 GBTU 00000098)
ACPI: HPET id: 0x8086a201 base: 0xfed00000
hpet clockevent registered
HPET: 4 timers in total, 0 timers will be used for per-cpu timer
hpet0: at MMIO 0xfed00000, IRQs 2, 8, 0, 0
hpet0: 4 comparators, 64-bit 14.318180 MHz counter
rtc0: alarms up to one month, 242 bytes nvram, hpet irqs
$

artur
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