Virtual Memory - WTH?

[deanops]

so, i was looking in activity monitor today (i found that a fan widget was causing the processor to be running at 80% , for the last 2 weeks, causing, ironically, my fans to be constantly on), and i saw virtual memory to be using 16.75 gb - WHAT DOES THIS MEAN?

first, what is virtual memory?
second, is this normal?
third, is this consuming my hd space?


any elp, explanation etc will be much apreciated

 

[TBi]

Well virtual memory is just that, virtual memory. This is when the OS uses the hard drive as virtual RAM. A program thinks it has access to a massive load of ram but in actuality it is "paged" out to the harddrive.

If a program needs 16GB of ram and you only have 2GB then 2GB will be active in main ram but the other 14GB's will be constantly written and read from the hard disk.

 

[Makosuke]

It's actually a little more involved than that (here's one article that a quick Google search turned up), but basically yes--that's how much RAM those programs COULD use, if for some reason they really wanted to.

It's totally normal, regardless, and really, the only thing you need to pay much attention to is the total of "Wired" and "Active" memory in use. So long as both of those aren't consuming all of your available physical RAM, you're fine.

 

[deanops]

so, this isnt good?

 

[AlBDamned]

so, this isnt good?

Widgets are traditionally really bad RAM hogs. If that TV one is causing problems I'd get rid of it.

I have a max of half a dozen widgets open with 1GB RAM and even though they're simple like Weather, World Clock, Calculator and dictionary, they're the first to go if I need to be doing stuff like video editing.

 

[flopticalcube]

so, this isnt good?

I'd say your a good candidate for more RAM.

 

[Eidorian]

I'd say your a good candidate for more RAM.

2.5 GB at least for now.

 

[mkrishnan]

18 gigs does seem like a large swapfile for a computer with 2GB of memory, though... what have you been doing? My iMac has 2GB of memory and it's been on for 33 days, and it has an 8GB swap file....

 

[Sun Baked]

I tried the fan widgets twice, after both times I had to delete all my preferences to fix something the evil little bugger did.

 

[dpaanlka]

I am finding more and more Macs with like five thousand widgets active at all times, half of them PowerPC and owners wondering why the systems are running so slow.

People seem to think they can have all the widgets they want without any detrimental effect - you have to remember they're basically little programs and each one uses resources just like any regular program.

 

[deanops]

hrmphh... is 1.5gb good enough? cos i only have 1gb now, wich is split into 2 512mb, so if i get another 1gb stick will that be good? and wheres the cheapest place in Australia to buy?

What else could i do?

thanks for all the informative responces, but do you really think 2.5gb is a minimum for internet, transmission, itues, iphoto, pages and numbers? oh and eye tv, qt, stickeis, adium and preview?


hmph... leopard, memory and hd... ****

 

[Chris F]

You have a ton of page in/outs which means lots of VM action is going on which means you would greatly benefit from having more memory in your computer. I suggest buying yourself a 2GB stick ($130 or so) and replacing one of your 512MB modules with it. You should notice a significant improvement in overall system speed.

 

[Eidorian]

I am finding more and more Macs with like five thousand widgets active at all times, half of them PowerPC and owners wondering why the systems are running so slow.

People seem to think they can have all the widgets they want without any detrimental effect - you have to remember they're basically little programs and each one uses resources just like any regular program.

I thought I was the only person encountering the same situation with PowerPC users. I have 2 GB of RAM and only run 6 widgets. Even I think that's excessive.

 

[AlBDamned]

You have a ton of page in/outs which means lots of VM action is going on which means you would greatly benefit from having more memory in your computer. I suggest buying yourself a 2GB stick ($130 or so) and replacing one of your 512MB modules with it. You should notice a significant improvement in overall system speed.

Tis a good suggestion. I'm in the same boat but this is a work computer so less chance to upgrade. I'd max it out if I could but a 2GB stick, then later upgrade the remaining 512MB one, seems like the best route.

 

[dpaanlka]

Do the Page ins/outs do like an average over a recent period of time, or do they just accumulate over time? Like, if I have my Mac Pro with 4 GB of RAM on for a month straight, even with light use would I end up with more Page ins and outs than a person with 512 MB of RAM using 16 applications and 40 widgets over a 2 hour period?

I thought I was the only person encountering the same situation with PowerPC users. I have 2 GB of RAM and only run 6 widgets. Even I think that's excessive.

4 GB and only 5 widgets lol...

 

[0007776]

Do the Page ins/outs do like an average over a recent period of time, or do they just accumulate over time? Like, if I have my Mac Pro with 4 GB of RAM on for a month straight, even with light use would I end up with more Page ins and outs than a person with 512 MB of RAM using 16 applications and 40 widgets over a 2 hour period?

The page ins/outs I think accumulate over time. all that matters is the ratio of page ins to page outs.

 

[Chris F]

What you see in Activity Monitor is the cumulative page in/outs since the system started up. Memory management is really complicated but generally speaking you would prefer not to see a lot of page outs as this indicates the system can not reclaim inactive memory and is swapping active memory to disk instead of holding it in cache.

Here is a good resource on the topic:
http://developer.apple.com/documentation/Performance/Conceptual/ManagingMemory/index.html

 

[disconap]

Ok, I have zero pageouts, 4.5gb of RAM (3.12gb free) and a virtual RAM size of 8.5gb. I have plenty of drive space, so I don't care too much, but it does have me scratching my head...

 

[deanops]

ok... this are the stats from istat
and this is my current activity monitr in all... also, what are page in/out and how do they affect me? what else can i do?

 

[flopticalcube]

Buy more RAM and clean out your hard disk. You are running low there too. And in the mean time, don't run so many widgets at once.

 

[AlBDamned]

Yep, OS X apparently needs a good 10GB of HDD space to run efficiently. At least consider a an external drive with space for backup and storage and dump some stuff on there, or look at getting a bigger internal HDD.

 

[MacNut]

Restarting the computer should make a big difference. It will clean out the memory. I wish Apple would make an on off switch for dashboard.

 

[disconap]

If you never initially use Dashboard, it doesn't start up. Otherwise you can just close your widgets when you're not using them and re-add them when you need them. Which does sort of defeat the purpose, but then I've never really seen the benefit of Widgets anyway...

 

[Sun Baked]

Pageouts are a good indicator of needing memory, BUT only if you are checking them after a restart -- and running you typical work cycle on your big application.

Sleep, long period of uptime, and swapping apps like a monkey on crack on a system with a lot open at once tend to distort pageouts and make the number big.

But for the above MacBook, adding $40 worth of RAM will make a difference as will adding a 2GB DIMM. 23hrs of uptime still isn't a lot. And there are more pageouts than pageins during that period.

 

[deanops]

Pageouts are a good indicator of needing memory, BUT only if you are checking them after a restart -- and running you typical work cycle on your big application.

Sleep, long period of uptime, and swapping apps like a monkey on crack on a system with a lot open at once tend to distort pageouts and make the number big.

But for the above MacBook, adding $40 worth of RAM will make a difference as will adding a 2GB DIMM. 23hrs of uptime still isn't a lot. And there are more pageouts than pageins during that period.

so am i better off buying 1gb of ram for about $AUD100, or a 2gb stick for $200 - remebering that most likely in the future prices for both will drop considerably,,..

im still pssed that i can get 2gb from america for $120US, but oh well