svn commit: r274739 - head/sys/mips/conf

[Warner Losh]

> On Nov 24, 2014, at 4:16 PM, Dag-Erling Smørgrav <des at des.no> wrote:
> 
> Mark R V Murray <mark at grondar.org> writes:
> 
>>> On 24 Nov 2014, at 15:01, Ian Lepore <ian at FreeBSD.org> wrote:
>>> 
>>> 
>>> The logging change was pretty simple:
>>> 
>>> Index: kern/subr_bus.c
>> 
>> Thanks.
>> 
>>> The low number of devices is pretty typical. Sometimes there'll be
>>> another uart.  Sometimes an i2c eeprom.
>> 
>> OK - a good example of a low-entropy system then.
>> 
>>> I have no idea what's up with the first 3 unchanging numbers, but I
>>> suspect a big part of the explanation for the other numbers is the 32KHz
>>> clock it's getting the numbers from.  There used to be a clock running
>>> at about 2.8MHz, but the source code for that driver seems to have
>>> disappeared from FreeBSD at some point between 8.x and -current.
>> 
>> What really bothers me is that these should be the difference between
>> 2 essentially similar numbers; times not all that far apart, yet some
>> of the numbers are truly massive.
> 
> They're not just massive, they're preposterous, as is the fact that most
> of them are absolutely identical, or just one bit off, from one run to
> the next.  My best guess is that get_cyclecount() is broken.

What’s the minimum specs required for get_cyclecount()? Not all of the
boxes that Ian was posting about have high-resolution time-keeping counters
in hardware… Maybe there’s some underlying expectation for this function
that these systems either aren’t providing or can’t provide.

Warner
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