How to Tell if Your Mac Needs More RAM

| MGG Answers

Question:

Jordan Writes: My new 2011 iMac with 4GB of RAM is feeling a bit sluggish while running Lion and doesn’t seem much faster than my old Mac.  I noticed in Activity Monitor that some numbers in the System Memory tab are very large.  Is something wrong with my Mac?  Do I need more RAM?

Answer:

In the System Memory tab of Activity Monitor, there are two important numbers to look at when diagnosing sluggish system performance: the amount of free RAM and the amount of Swap Used. 

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Free Memory and Swap Used are key values to determining RAM requirements.

Free RAM is the amount of memory that is unused by any process on the system and is ready to be assigned when needed.  If this number consistently falls below 50 MB, it is the first sign that your system needs more RAM.  To find out for sure if more RAM is the answer, look to Swap Used.  Swap Used tells the user how much space on the hard drive is currently in use because the system needed more RAM than was available.  There will usually be between 100 and 200 MB of Swap on a system with adequate amounts of RAM, but if that number grows into the gigabytes, it is a clear indicator that more RAM is required.

Good sources for additional RAM are Crucial, Other World Computing, and Ramjet.

This question was originally answered on MGG 355: Sometimes Files Miss The Trash Can

About MGG Answers:

Each week Dave Hamilton and John F. Braun provide some great troubleshooting advice to listeners of the Mac Geek Gab podcast. Here with MGG Answers we share some of those tips with the rest of the world!

Comments

furbies

Jim

I’m on a: Mac Pro Quad 2.66 / 5GB RAM Early 2009 Mac OS X 10.6.8

I use an app called MemoryStick
It tells me that I’m currently running 3 swap files.

Is lots of swap files bad ?

furbies…

Jim Tanous

Is lots of swap files bad ?

Hey furbies,

No, the number of swap files, in and of itself, is not a bad sign.  OS X will create a number of small swap files of incremental size.  For example, I currently have four: 67.1 MB, 67.1 MB, 134.2 MB, and 268.4 MB.  If I were to get much more and the total size rose into the gigabytes, that would be a sign that I need more RAM.  In your case, three should be just fine.  Keep an eye on the total swap size reported in Activity Monitor.  If you see that number consistently go over 1 GB, get some more RAM.

FYI, your particular Mac Pro can unofficially support a maximum of 32 GB of RAM using 8 GB modules.

furbies

furbies said:

Is lots of swap files bad ?

Hey furbies,

No, the number of swap files, in and of itself, is not a bad sign.? OS X will create a number of small swap files of incremental size.? For example, I currently have four: 67.1 MB, 67.1 MB, 134.2 MB, and 268.4 MB.? If I were to get much more and the total size rose into the gigabytes, that would be a sign that I need more RAM.? In your case, three should be just fine.? Keep an eye on the total swap size reported in Activity Monitor.? If you see that number consistently go over 1 GB, get some more RAM.

FYI, your particular Mac Pro can unofficially support a maximum of 32 GB of RAM using 8 GB modules.

Well, currently Activity Monitor reports: Swap used: 30.6MB
So I guess I’m ok at the moment.

Would be nice to max it out at 32GB. If only I had the money…......

regards

furbies

RayCon

I’ve got 16 GB of RAM in my iMac i7 27 inch.  It says it has, give or take, about 70 to 80 MB free, and it’s swapping 15 GB.  What is going on here?

Guru

Thanks for this great tip, so as I checked I see my free RAM is 860 MB which is good but my swap is in 1.74 GB. I dont see my machine is slow but if I start using Xcode and other heavy stuff i see it takes time to run e.g. debugger.

Is it reasonable to say I need more ram?

Thanks
guru

Dave Hamilton

RayCon - you’ll want to use activity monitor to look and see what app is using all that virtual memory. You do this by first choosing View->Columns and make sure “Real Shared Memory” is checked. Then sort by the “Shared Mem” column and look for the big offender. That column tells you exactly how much virtual memory any given app is using. You can also sort by the “Real Mem” column to see how much physical RAM any given app is using. Sounds like this is material for its own MGG Answers, comng soon to a TMO near you!

Dave Hamilton

Guru - you’re probably on the fence. The reality is we all could do things that push us over our limits, the question is how often we’re doing them. Check your machine once or twice/day for the next few days and see where you average out. If you’re consistently over 1GB of swap used, then yeah, you could certainly use more.

LarryR

My rule of thumb is this:
If I have less than the maximum installable RAM, I need more RAM.

RayCon

Well, I started quitting apps and noted an improvement, but not terribly so.  With the utilities I have, I noticed that the machine had been running without reboot for 4+ days, and because there was a software update that required a reboot anyway, I eventually did that.  I still have my major apps running (Safari, Mail, DEVONthink, Skype, etc.), but it’s now showing consistently more than 8 GB free with NO swap being used.  I wonder if it’s just “build-up.”  Isn’t there a way to clear the swap cache (or whatever it’s called) without rebooting?  Otherwise, I’ll just have to remind myself to do this on a regular basis.  I WILL, as suggested, be checking the activity monitor daily.

Mikuro

RayCon, OS X should be able to run for MONTHS without a reboot without it getting to a state like that. There’s definitely something wrong on your system. Keep an eye on Activity Monitor and try to see what’s using all that RAM as time goes on.

I only reboot about once a month or so (for system updates). I’ve currently been up 8 days and still have zero swap use (MacBook Pro, 8GB RAM).

Guru

Thanks for reply. I will keep checking on Activity Monitor. One thing to mention after reading RayCon’s comment ..I too hardly reboot my mac unless any OS patch or app updates demand it.

Is that good practise?

Mikuro

I think that’s pretty much normal. The days of shutting down every night are long gone.

If you’re having strange issues, I recommend downloading Onyx and manually running the daily/weekly/monthly maintenance scripts. This is usually done by the system automatically, but sometimes it can get thrown out of whack. I like to manually run them once in a blue moon.

Ross Edwards

I have plenty of RAM, apparently.  As long as I’m not running Flash.

Damn… half a gig to a gig of RAM usage, continuous!  Absolute gluttony!  Nothing else is even in the neighborhood.  Far back in second place is Crashplan with 50MB (which still seems like a lot if you ask me).

UpQuark

As long as I?m not running Flash.

 

The key here too is that Safari, by itself,  is also a memory hungry app with ‘memory leaks’ aplenty.

Just restarting Safari or shutting it down when not in use will help the memory issue.  If I have several tabs open and the web pages has javascript that forces auto refresh periodically, Safari will quickly bloat.  Googles’ news aggregator page news.google.com is a good illustration of this phenomenon.  In the case of news.google.com, I haven’t done memory testing with other browsers to validate if the issue is solely within Safari or due to news.google.com. 

But as with the author and other commenters, Activity Monitor or like application is a good place to start.  (I use iStats Menu 3)

My new iMac is 27” 12Gigs RAM 3.14 Ghz i7.  I too run into swap occasionally if I have several apps open including Xcode for iPHone dev, Safari, Chrome, iTunes, Adium, Acorn or Pixelmator, VueScan, and others.  Of that list, if I close Safari, my swap issues fade dramatically.

In writing this response, “WebProcess” grew from 130MB to 200MB in the span of approximately 7 minuets.

Steve

Another way to tell that your Mac needs more RAM: You have Safari 5.1 installed.

furbies

Well I’ve been monitoring the “Swap used” for the last day and it’s hovering around 21.1 MB.

I’ve tried doing all the usual things I do on my Mac and it’s stayed around 21 / 22 MB Swap used.

So I guess I’ve got to find another compelling reason to add some more RAM to my Mac Pro…...

Mind you, my VM size is 169.18 GB (But I know this isn’t an important number / stat)

furbies

So I guess I?ve got to find another compelling reason to add some more RAM to my Mac Pro?...

I found a compelling reason…..

The Australian Dollar is down, and if the GFC v2 comes then the $AU may take a tumble…....

(Anyway it’s an excuse, and I’m using it!)

Just ordered another 8GB (2 x 4GB)

fyi: Currently my Swap used: is 30.8MB

furbies

Just ordered another 8GB (2 x 4GB)

fyi: Currently my Swap used: is 30.8MB

Well, now I have 11GB installed and for an hour I had “Swap used: 0 bytes” And that’s after also replacing one of the HDs and Time Machine spending an age purging 200GB of old backups, so it could “do” the new HD.

But it didn’t last. Now “Swap used: 14.8MB”

(Sensitive folks might want to look away now)

Bugger!

I realise that 14MB isn’t really much at all, but I had hoped…..

Now the question is. Are there any tweaks I can safely do that will convince the Mac Pro & OS to take full advantage of all that lovely extra RAM ?

Dave Hamilton

Now ?Swap used: 14.8MB? [...]
I realise that 14MB isn?t really much at all, but I had hoped?..

Now the question is. Are there any tweaks I can safely do that will convince the Mac Pro & OS to take full advantage of all that lovely extra RAM ?

The reality is that this is absolutely normal. I have 12 GB RAM in my iMac, 2GB completely free, and I still have a little swap used. That much is normal, and Jim indicated this in the article. It’s just a function of the way UNIX (and OS X) manage memory. Now if that swap number grows up to more than a couple hundred megabytes, you have a problem, but 15 is no worry at all.

geoduck

OK I know this is an old thread but one more question if I may.

I noticed my Mac (2008 MacBook 4Gb RAM) was slowing down. Safari was using a pile of memory so I rebooted the system (something that hadn’t happened in a few weeks. Swap is down to 0 and free is up to 2.93Gb. All is well.

However I noticed that VM size is HUGE: 123Gb. Before rebooting it was over 160Gb. I noticed in the graphic with the article that for your system it’s at 185Gb.

What is the VM? Why does it take so much RAM? Would this impact performance?

furbies

Update for the curious:

Mac Pro Quad 2.66 (early 2009)
Mac OS 10.6.8
11GB ram

uptime 11 days, 12 hours

Running 3 swap files 2 x 67.1mb and 1 x 134.2: for a total of 268.4mb

And from Activity Monitor:
free: 6.26 GB
wired: 780.7 MB
active: 3.42 GB
inactive: 560.9 GB
used: 4.73 GB

page ins: 2.90 GB
page outs: 12.2 MB
swap used: 47.6 MB

I’ve been recording tv in EyeTV, re-encoding many many GBs of AVI with Elgato Turbo H.264HD, as well as surfing with Safari, iTunes(ing), Screen Sharing into a MDD G4 etc

So the adage, more ram is better does seem to be true…......

Joe Kenny

Hi.

Just a quick question.
I’ve done all the checks and found out that i do actually need more RAM…but my question is - why? What is it that I’m doing, along with other people, that means I need more RAM?

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