lkml.org 
[lkml]   [2009]   [Mar]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [Patch] Fix the possibility of insane return value of hpet_calibrate() against SMI.
Yasunori Goto wrote:
> Sorry for late response.
>
>
>> Yasunori Goto wrote:
>>
>>>> I've no sense of feel for how long each calibration run would take.
>>>> Would doing it 5 times show up as a significant increase in the boot
>>>> time for those that care about boot time being as quick as possible?
>>>>
>>> Hmm. The loop times is trade off against reliable value....
>>> Though SMI is rare interruption, I don't know how frequent
>>> hypervisor's switch is.
>>>
>> Could you, just for testing, run the calibration five thousand times or
>> so instead of five times, and count how often you get insane values?
>> (And how much delay does such an SMI add?)
>>
>
> I tried 50000 times. But insane value was nothing.
> I think SMI is very rare.
>
>
>>> Each calibration of this has 1 milli second.
>>> Do you think 5 msec is too long?
>>>
>> This shouldn't matter when booting. Anyway, I think it's possible to
>> increase TICK_CALIBRATE without losing too much accuracy.
>>
>
> Hmm. If the person who is trying to reduce boot time for fastboot dislikes this impact,
> then I'll try Vojtech-san's way.
>

That probably makes sense -- if it is extremely rare, and if you get two
values that are the same (within some small delta) then you probably
are 99.99% confident that you have the right data.

Paul.

>
> Thanks.
>



\
 
 \ /
  Last update: 2009-03-17 14:17    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site