sleeping processes and swap

[Dale Farnsworth]

lthielster at gmail.com wrote:
> You are probably right but I do not understand why lshw tells you he has 6
> slots (5 used) with 4x64Mb and 1x128Mb if he really only has 3 physical
> slots.  Was there something about the design of stcks using smaller memory
> chips that would cause this?  Something else? And how can you tell from that
> listing?

There are 2 banks per physical slot.  3 physical slots gives 6 banks.
The first 2 two DIMMs each use 2 banks of 64MB each.  The 3rd DIMM uses
a single bank of 128MB; that leaves the last bank unused.  Typically,
DIMMs use one bank for each "side"---double-sided DIMMS use 2 banks and
single-sided DIMMs use 1 bank, but there are exceptions.

Numbering from 0, Michael has:
physical slot	DIMM	bank A number / size	bank B number / size
	0	128MB		0 / 64MB		1 / 64MB
	1	128MB		2 / 64MB		3 / 64MB
	2	128MB		4 / 128MB		5 / 0MB

Electrically, the memory controller, and thus the software, only
sees banks, not physical slots.  So lshw can only report about banks.
Unfortunately, lshw refers to banks both as "banks" and as "slots",
which is confusing.  At least in this lshw output, you should read
"slots" as "banks".

-Dale

> On 28 Nov 2006 14:53:23 -0000, Dale Farnsworth <dale at farnsworth.org> wrote:
> >
> > In article <op.tjqb7rchjr3qzh at localhost.localdomain> Mike wrote:
> > > lshw? List Hardware? That's a new one! I always thought there was a
> > > command like this! Thanks for sharing. I had to apt-get it but here is
> > > what the relevant section says.....
> > >
> > >       *-memory
> > >            description: System Memory
> > >            physical id: 21
> > >            slot: System board or motherboard
> > >            size: 384MB
> > >            capacity: 512MB
> > >          *-bank:0
> > >               description: DIMM EDRAM
> > >               physical id: 0
> > >               slot: BANK_0
> > >               size: 64MB
> > >          *-bank:1
> > >               description: DIMM EDRAM
> > >               physical id: 1
> > >               slot: BANK_1
> > >               size: 64MB
> > >          *-bank:2
> > >               description: DIMM EDRAM
> > >               physical id: 2
> > >               slot: BANK_2
> > >               size: 64MB
> > >          *-bank:3
> > >               description: DIMM EDRAM
> > >               physical id: 3
> > >               slot: BANK_3
> > >               size: 64MB
> > >          *-bank:4
> > >               description: DIMM EDRAM
> > >               physical id: 4
> > >               slot: BANK_4
> > >               size: 128MB
> > >          *-bank:5
> > >               description: DIMM EDRAM [empty]
> > >               physical id: 5
> > >               slot: BANK_5
> > >
> > > Hmmmmm... looking at the output it seems as if I had a dishonest
> > salesman!
> > > I bought 3 128MB chips (so he said). I don't know what this 'slot 5' is.
> >
> > Calm down.  No need to jump to erroneous conclusions.  The above shows 3
> > 128MB DIMMS.  Each slot has 2 banks.  Two of the DIMMs use 2 64MB banks
> > each and one DIMM uses a single 128MB bank.
> >
> > In theory, you could put in two 256MB DIMMs for a total of 512MB,
> > but I wouldn't add more memory without replacing the motherboard/cpu.
> >
> > Let's back up a bit.  Nothing you have shown would indicate that you
> > are low on memory.  See below.
> >
> > > All of the RAM slots have something in them and there are only 3. It
> > must
> > > be something to do with the manufacturing and onboard memory.
> > >
> > > I really appreciate your guys help.
> > >
> > > 3852645 KB =  total memory
> > > 768 M = system memory + banks 0, 1, 2, 3, and 4. Is my system really not
> > > accessing all of it's memory?
> >
> > Redo your arithmetic, you have 384MB.
> >
> > > bmike1 at 1[~]$ top
> > > top - 07:04:21 up 48 min,  2 users,  load average: 3.86, 2.94, 2.46
> > > Tasks:  86 total,   4 running,  82 sleeping,   0 stopped,   0 zombie
> > > Cpu(s): 66.4% us, 29.6% sy,  0.0% ni,  0.3% id,  0.3% wa,  2.9% hi,
> > 0.5%
> > > si
> > > Mem:    385264k total,   356868k used,    28396k free,    14972k buffers
> > > Swap:  1025000k total,        0k used,  1025000k free,   172972k cached
> >
> > This looks good.  You are not low on memory.  In fact, you're not using
> > any swap space.  You have the misconception that having a low number for
> > the "free" number above is a bad thing.  It is good.  A good OS tries
> > to minimize this number.
> >
> > Memory is used for three broad categories-- active, IO buffers and cached.
> > From the above, you have 385264K total memory.  172972K is cached,
> > meaning that it holds data or programs that are currently unused but
> > might be re-used in the near future.  14927K is currently used for I/O
> > buffers.  Approximately 385264K - (172972K + 14927K) = 197320K is in
> > active use.
> >
> > I repeat, a low value for free memory doesn't indicate high memory
> > contention.
> >
> > While, in general, it is good to use programs that minimize their memory
> > use, you don't need to be overly concerned at this point.  Your system
> > is not "out of memory".
> >
> > From the "top" output that you previously posted, it looks like opera,
> > X, and a terminal program are using all of your cpu.  I suspect that's
> > why your system feels sluggish.
> >
> > -Dale