Re: where is my memory?

[matthew sporleder <msporleder%gmail.com@localhost>]

On Tue, Sep 21, 2010 at 9:56 PM, Steven Bellovin 
<smb%cs.columbia.edu@localhost> wrote:
>
> On Sep 21, 2010, at 5:51 34PM, matthew sporleder wrote:
>
>> On Tue, Sep 21, 2010 at 5:38 PM, Matthew Mondor
>> <mm_lists%pulsar-zone.net@localhost> wrote:
>>> On Sun, 19 Sep 2010 15:13:59 -0400
>>> matthew sporleder <msporleder%gmail.com@localhost> wrote:
>>>
>>>> So I've recently been exploring a pretty common mystery on netbsd
>>>> machines- where is my memory?
>>>
>>> I'm not sure this answers your questions, but the dmesg of a system
>>> here (also with 2GB RAM) has:
>>>
>>> total memory = 2047 MB
>>> avail memory = 1999 MB
>>>
>>> I assume some pages are reserved and/or used for PMMU tables, etc...
>>> --
>>> Matt
>>>
>>
>> total memory = 256 MB
>> avail memory = 239 MB
>>
>> So that works well with the vmstat -s numbers.  However, that still
>> doesn't really explain where that memory is.
>>
>> I guess top should be patched or something to reflect the vmstat -s
>> numbers instead of whatever it's currently using.
>>
>> Would you mind looking at vmstat -s and see if you're missing 48MB?
>
> Some graphics chips, especially on lower-end machines, use main memory, thus 
> making it unavailable to the CPU.
>

On my soekris with no video card:

total memory = 127 MB
avail memory = 113 MB

Oddly on this box physmem and usermem are the same:
hw.physmem64 = 133820416
hw.usermem64 = 133820416

vmstat -s shows:
119787520 bytes managed == avail memory from dmesg.

So can I get a hint on where dmesg is calculating these two numbers
and where that allocation goes?