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To: Brandon Gooch <jamesbrandongooch@gmail.com>
From: Ian FREISLICH <ianf@clue.co.za>
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Date: Thu, 02 Sep 2010 11:20:03 +0200
Cc: Alexander Motin <mav@freebsd.org>,
	FreeBSD-Current <freebsd-current@freebsd.org>
Subject: Re: One-shot-oriented event timers management 
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On Wed, Sep 1, 2010 at 2:16 PM, Alexander Motin <mav@freebsd.org> wrote:
> Brandon Gooch wrote:
>> This latest patch causes an interrupt storm with the HPET timer on my
>> system. The machine took about 8 minutes to boot and bring me to a
>> login prompt. System interactivity (i.e. input from keyboard, output
>> on console) was fine, but after checking the output of `systat vmstat
>> -1`, I saw the interrupt rate on each HPET entry was over 120k!
>>
>> Can I provide any useful detail? Of course, test patches are always welcom
e :)
>
> I was able to reproduce alike storm in some situations.
>
> Try new version: http://people.freebsd.org/~mav/timers_oneshot7.patch

Interrupt rates are definitely reduced.

[mini] /usr/home/ianf $ vmstat -i
interrupt                          total       rate
irq1: atkbd0                        1154          1
irq9: acpi0                        10829         15
irq16: ath0 uhci3+                 16226         23
irq18: uhci2                          16          0
irq19: uhci1+                       7090         10
irq20: hpet0                      169288        240
irq23: uhci0 ehci0                    64          0
irq256: hdac0                        187          0
Total                             204854        291

[mini] /usr/home/ianf $ sysctl dev.cpu |grep usage
dev.cpu.0.cx_usage: 0.00% 0.04% 0.80% 99.15% last 1601us
dev.cpu.1.cx_usage: 0.00% 0.00% 0.65% 99.34% last 2078us

Ian

-- 
Ian Freislich