hw.physmem/hw.realmem question

[Wojciech Puchar]

>  AMD Features2=0x1<LAHF>
>  TSC: P-state invariant, performance statistics
> real memory  = 34359738368 (32768 MB)
> avail memory = 32191340544 (30700 MB)

2GB memory "disappears" too even when you don't set anything.

i asked such a question for other machine some time ago without much 
answer.


in your laptop it may be shared graphics memory reserved by chipset

still on my dell server

real memory  = 34359738368 (32768 MB)
avail memory = 33166921728 (31630 MB)

i have over 1GB unavailable and it doesn't have shared graphics memory.

it would be nice to be able to look exactly how memory is used.


> Event timer "LAPIC" quality 600
> ACPI APIC Table: <DELL   DCSRADON>
>
> and from sysctl:
> hw.physmem: 34284916736
> hw.usermem: 32964923392
> hw.realmem: 36507222016
>
> after setting
> 	hw.physmem=16G
>
> from dmesg:
> real memory  = 34359738368 (32768 MB)
> avail memory = 13999382528 (13350 MB)
>
> and sysctl:
>
> 	hw.physmem: 14957563904
> 	hw.usermem: 10094678016
> 	hw.realmem: 17179869184
>
> from the numbers, I can assume that realmem is the real physical memory,
> (or whatever is set in hw.physmem),
> if so, where did almost 2G go? (realmem - physmen)
>
> the only info I found so far is:
> from loader(8):
>
>     hw.physmem    Limit the amount of physical memory the system will use.
>                   By default the size is in bytes, but the k, K, m, M, g and
>                   G suffixes are also accepted and indicate kilobytes,
>                   megabytes and gigabytes respectively.  An invalid suffix
>                   will result in the variable being ignored by the kernel.
>
> what is physmem and realmem, and what's the relationship - if any - between
> them?
>
> cheers,
> 	danny
>
>
>
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