Solved. More RAM. Is it cost effective?

mikep · 8 May 2015 23:19

I’m running Ubuntu 14.04 dual booted with XP on a core2 duo machine with 4GB of RAM.

I routinely use VMs in Virtualbox.

I’m thinking of doubling the RAM, but I can’t decide whether I’d see enough of an improvement to justify a £56 investment.

Any thoughts appreciated…

M

Mark_Greaves_PCNetSp · 8 May 2015 23:57

If your system is low on RAM and using the swap partition then yes you’d notice a BIG difference

If it’s not using the swap partition then you’re unlikely to notice any difference at all

If I had to guess I’d say with 4GB and if you’re running a single XP VM (using the virtualbox default memory settings) you’re unlikely to be using the swap partition … but this obviously depends on what else you have the host OS doing.

Do what you normally do, and when you consider the system “under load” open a terminal and run:

free -m

if “swap used” says anything other than 0 you’ll benefit from more RAM (or possibly just changing the “swappiness” setting … the point at which the system starts to use the HDD as memory)

mikep · 9 May 2015 22:51

Thanks Mark,

Swap used is resolutely sticking at zero,with one (XP) VM running, even while streaming live TV on the host.

But as soon as I run up a Linux Mint VM as well, things grind to a halt and the swap file is used. I’m unlikely to use multiple VMs simultaneously, however, so I think I’ll keep that £56 in my pocket, despite the fact that received wisdom says that more RAM is always good.

Cheers.

M

Mark_Greaves_PCNetSp · 10 May 2015 12:31

I’d check how the system is with just a Mint or Ubuntu VM running … remember XP was lighter than the current versions of Ubuntu/Mint, and MUCH lighter than Win Vista/7/8 … I think virtualbox automagically allows more RAM for a Win7/8 VM now.

It really depends on what you’re planning to do though

If I were you I’d also consider changing your “swappiness” setting from the default 60 to something like 10 … swap will only get used when it’s getting critical to do so (down to 10% RAM left).

Run:

cat /proc/sys/vm/swappiness

and I’d expect it to be set to the default
60
meaning your system will start to use swap when 60% of RAM is remaining (this made sense when systems had small amounts of RAM but not not so much with 4GB)

Now let’s change that to a swappiness of 10 (swap only starts to be used when there’s 10% RAM remaining) … run:

sudo gedit /etc/sysctl.conf

and add these 2 NEW lines at the bottom

# Set swappiness to 10 (added by mikep)
vm.swappiness = 10

SAVE the file, then reboot.

after rebooting, run:

cat /proc/sys/vm/swappiness

and hopefully it’ll now return
10

mikep · 14 May 2015 10:31

Thanks Mark,

Swappiness now at 10 and things are much better with 2 VMs running (XP & Mint).

Much appreciated.

M

mikep · 23 May 2015 21:37

Mark,

Things still going well, but I’m baffled by the results of free -m.

Total memory shows as 3952, used as 3838, free as 113, shared 48, buffers 241 and cached 1628.

I suspect this means almost all my RAM is being used (but swap isn’t), and that we’re talking gibibytes, not gigabytes. Can you enlighten me please?

Also - if almost all my physical RAM is indeed in use, would there be any benefit from installing more? I suspect not (based on your first reply), but I seem to be sailing close to the wind…

M

mikep · 24 May 2015 02:07

Getting a bit concerned Mark. You usually respond much quicker.

I hope everything’s OK?

Mark_Greaves_PCNetSp · 24 May 2015 15:04

Just busy with the build up to the Peppermint 6 release

I suspect this means almost all my RAM is being used (but swap isn't), and that we're talking gibibytes, not gigabytes. Can you enlighten me please?

Neither … free is talking bytes.

but I seem to be sailing close to the wind

Well if you load anything else it’ll start to swap, and things will slow considerably … so it’s up to you if you think more memory is worthwhile, or if you just wanna keep an eye on what you have loaded at any one time.

mikep · 24 May 2015 19:49

Glad you’re ok (I wasn’t pushing for a response, just a bit concerned at a 10 day gap, which isn’t normally like you).

M

Mark_Greaves_PCNetSp · 24 May 2015 20:08

You only posted the questions yesterday ??

mikep · 24 May 2015 20:38

But I told you I’d changed the swappiness on May 14th…

You usually respond to feedback (not that it’s necessary) so I suppose I kind of expected a “You’re welcome” or something of that nature. Just got slightly worried at what I thought was a prolonged absence, based on your normal M.O.

Glad to know you’re not slumped over a keyboard in sunny Kernow!

Mark_Greaves_PCNetSp · 24 May 2015 20:56

Nah, still kickin

Melissa · 11 September 2015 02:17

I need more RAM but can’t afford it right now; I think we did the swap thing for me ages ago- could I check it with you please Mark? (Peppermint 3 on the laptop).

Mark_Greaves_PCNetSp · 11 September 2015 14:10

What’s the output from:

free -m

and

cat /proc/sys/vm/swappiness

Melissa · 11 September 2015 23:50

melissa@melissa-HP-Compaq-nx6325-RH628ES-ABU ~ $ free -m
total used free shared buffers cached
Mem: 685 587 97 0 4 71
-/+ buffers/cache: 510 174
Swap: 701 215 486
melissa@melissa-HP-Compaq-nx6325-RH628ES-ABU ~ $ cat /proc/sys/vm/swappiness
60
melissa@melissa-HP-Compaq-nx6325-RH628ES-ABU ~ $

Thanks Mark- if you could tell me how much RAM I need to get I will write it down and keep it safe! I have to reboot a lot when accessing a lot of videos in succession or having a few web pages open with tons of photos on them ( the laptop freezes and that stop script box comes up).

Mark_Greaves_PCNetSp · 12 September 2015 11:47

it will freeze … you’re using swap already.

What’s the output from:

sudo dmidecode --type 17

Melissa · 12 September 2015 13:47

dmidecode 2.11
SMBIOS 2.4 present.

Handle 0x000B, DMI type 17, 27 bytes
Memory Device
Array Handle: 0x000A
Error Information Handle: No Error
Total Width: 64 bits
Data Width: 64 bits
Size: 256 MB
Form Factor: SODIMM
Set: None
Locator: DIMM #1
Bank Locator: Not Specified
Type: DDR2
Type Detail: Synchronous
Speed: 667 MHz
Manufacturer: 7F7F7F7F7F510000
Serial Number: 0102F523
Asset Tag: Not Specified
Part Number: 64T32000HDL3SB

Handle 0x000C, DMI type 17, 27 bytes
Memory Device
Array Handle: 0x000A
Error Information Handle: No Error
Total Width: 64 bits
Data Width: 64 bits
Size: 512 MB
Form Factor: SODIMM
Set: None
Locator: DIMM #2
Bank Locator: Not Specified
Type: DDR2
Type Detail: Synchronous
Speed: 667 MHz
Manufacturer: 7F7F7F0B00000000
Serial Number: 8B152F02
Asset Tag: Not Specified
Part Number: M2N51264TUH8A2F-3C

melissa@melissa-HP-Compaq-nx6325-RH628ES-ABU ~ $

Mark_Greaves_PCNetSp · 12 September 2015 15:34

What you want is a 1GB or even better 2GB DDR2 667mhz (PC2-5300) SODIMM

such as:
http://uk.crucial.com/ProductDisplay?urlRequestType=Base&catalogId=10153&categoryId=&productId=10764&urlLangId=-1&langId=-1&top_category=&parent_category_rn=&storeId=10153

http://uk.crucial.com/ProductDisplay?urlRequestType=Base&catalogId=10153&categoryId=&productId=10815&urlLangId=-1&langId=-1&top_category=&parent_category_rn=&storeId=10153

see here:
http://uk.crucial.com/gbr/en/compatible-upgrade-for//business-notebook-nx6325

You could “get away” with 1GB + the 512MB you already have … but if at all possible, get the 2GB module

Melissa · 12 September 2015 15:48

Thanks, I will get 2GB once I have a paid job!

SeZo · 13 September 2015 09:22

You could try zswap:

Zswap is a lightweight, write-behind compressed cache for swap pages. It takes pages that are in the process of being swapped out and attempts to compress them into a dynamically allocated RAM-based memory pool. If this process is successful, the writeback to the swap device is deferred and, in many cases, avoided completely. This results in a significant I/O reduction and performance gains for systems that are swapping

Check if it is enabled in your kernel:

cat /boot/config-`uname -r` | grep ZSWAP

If that returns CONFIG_ZSWAP=y then good to go to enable it.