[gentoo-user] RAM installed vs reported

Thanasis

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Dec 30, 2009, 6:00:01 AM12/30/09

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I have a netbook (Acer Aspire One A110L) and installed a 1GB DDR2 in the
available slot, for a total of 1.5GB or RAM.
The BIOS reports it as 1.5GB and so does grml linux (booting from usb),
but the installed gentoo linux reports only 904600 kB:

# free
total used free shared buffers cached
Mem: 904600 82316 822284 0 9752 37712
-/+ buffers/cache: 34852 869748
Swap: 1638588 0 1638588

# cat /proc/meminfo
MemTotal: 904600 kB
MemFree: 822284 kB
Buffers: 9752 kB
Cached: 37712 kB
SwapCached: 0 kB
Active: 32232 kB
Inactive: 28780 kB
Active(anon): 13848 kB
Inactive(anon): 0 kB
Active(file): 18384 kB
Inactive(file): 28780 kB
Unevictable: 0 kB
Mlocked: 0 kB
SwapTotal: 1638588 kB
SwapFree: 1638588 kB
Dirty: 4 kB
Writeback: 0 kB
AnonPages: 13548 kB
Mapped: 11256 kB
Shmem: 300 kB
Slab: 10356 kB
SReclaimable: 6132 kB
SUnreclaim: 4224 kB
KernelStack: 1424 kB
PageTables: 892 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 2090888 kB
Committed_AS: 73552 kB
VmallocTotal: 122880 kB
VmallocUsed: 9688 kB
VmallocChunk: 109832 kB
DirectMap4k: 11832 kB
DirectMap4M: 905216 kB

I suspect it has to do with my kernel (2.6.32-gentoo-r1) configuration,
but do not know where to look.
Any suggestions ?

Dirk Heinrichs

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Dec 30, 2009, 6:20:02 AM12/30/09

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Am Mittwoch 30 Dezember 2009 11:49:39 schrieb Thanasis:

> I have a netbook (Acer Aspire One A110L) and installed a 1GB DDR2 in the
> available slot, for a total of 1.5GB or RAM.
> The BIOS reports it as 1.5GB and so does grml linux (booting from usb),
> but the installed gentoo linux reports only 904600 kB:

With more than 1G of memory, you should set CONFIG_HIGHMEM4G=y.

HTH...

Dirk

Thanasis

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Dec 30, 2009, 7:10:02 AM12/30/09

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I thought CONFIG_HIGHMEM4G had to do with more than 4GB of RAM.
Now I can see that the associated help says it is for an amount between
1 and 4GB.
That should be it. The option name confused me.
I will try it and report back.
Thanks :-)

Thanasis

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Dec 30, 2009, 9:10:01 AM12/30/09

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on 12/30/2009 01:08 PM Dirk Heinrichs wrote the following:

That did it !
Thanks again.
:-)

Thanasis

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Dec 31, 2009, 3:10:02 PM12/31/09

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on 12/31/2009 04:59 PM Krzysztof Halasa wrote the following:

> Thanasis <than...@asyr.hopto.org> writes:
>
>> I thought CONFIG_HIGHMEM4G had to do with more than 4GB of RAM.
>> Now I can see that the associated help says it is for an amount between
>> 1 and 4GB.
>

> Depends on the "split" used. With 2 GB : 2 GB you can have all-lowmem
> 1.5 GB RAM, without CONFIG_HIGHMEM*. 2 GB of per-process address space
> is usually not a problem.
How do you implement that? What do you mean 2GB:2GB split ?

Thanasis

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Jan 3, 2010, 7:10:02 AM1/3/10

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> See "make menuconfig", Processor type and features -> Memory split. You
> need to select "EMBEDDED" and "EXPERIMENTAL" first. What you need for
> 1.5 GB RAM is VMSPLIT_2G.
>
> The idea is that the CPU address space is divided: ca. 2 GB (in this
> configuration) for user space (for each process - instead of 3 GB),
> 2 GB - 128 MB (or something like that, I don't remember exactly) for
> physical RAM, and the last 128 MB or so for PCI devices and other
> things.
>
Hmm..., but are EMBEDDED options suitable for a netbook like the A110L ?

Thanasis

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Jan 3, 2010, 9:10:01 PM1/3/10

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on 01/04/2010 01:10 AM Krzysztof Halasa wrote the following:
> Thanasis <than...@asyr.hopto.org> writes:
>
>
>> Hmm..., but are EMBEDDED options suitable for a netbook like the A110L ?
>>

> This "EMBEDDED" just means "don't touch these unless you really know
> what you're doing".
>
> BTW I remember using VMSPLIT 2 GB : 2 GB on server-class machines,
> before they were upgraded to x86-64.
>
Do you mean that I should try it? Is there any gain over using
CONFIG_HIGHMEM4G ?

Joshua Murphy

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Jan 4, 2010, 11:10:02 AM1/4/10

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2010/1/3 Thanasis <than...@asyr.hopto.org>:

Likely nothing noticeable, but here's a bit of a good coverage of the topic:

http://kerneltrap.org/node/6067

--
Poison [BLX]
Joshua M. Murphy

Thanasis

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Jan 4, 2010, 1:00:02 PM1/4/10

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Thanks, I think I'll give it a try. :-)

Thanasis

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Jan 4, 2010, 3:10:02 PM1/4/10

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on 01/04/2010 04:51 PM Joshua Murphy wrote the following:

Which one option should I choose:
( ) 2G/2G user/kernel split
or
( ) 2G/2G user/kernel split (for full 2G low memory)
?

Thanasis

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Jan 4, 2010, 3:10:02 PM1/4/10

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I tried option: 2G/2G user/kernel split (for full 2G low memory), but X
would not start. So i reverted back to CONFIG_HIGHMEM4G.