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What's my bottleneck: CPU or RAM?

I

itom37

macrumors newbie
Original poster
Jun 20, 2006
7
0
Hi,

I have a mid-2007 MBP 2.2 GHz Intel Core 2 Duo with 2 GB of RAM.

My computer has slowed down quite a bit lately, so I'm considering a new MBP or MBA. I know that a MBA will be a downgrade in terms of processor speed, however, I wonder what is making my current computer slow, ie, will I feel the difference if I get a top of the line MBA.

I get the spinny beachball all the time now, whenever doing multiple applications at once. My MacStatPro widget usually says I have about 10-30 MB of "free memory", which seems low compared to my 2 GB.

So why is my computer slow? RAM? CPU? Something else?
 
itom37 said:
Hi,

I have a mid-2007 MBP 2.2 GHz Intel Core 2 Duo with 2 GB of RAM.

My computer has slowed down quite a bit lately, so I'm considering a new MBP or MBA. I know that a MBA will be a downgrade in terms of processor speed, however, I wonder what is making my current computer slow, ie, will I feel the difference if I get a top of the line MBA.

I get the spinny beachball all the time now, whenever doing multiple applications at once. My MacStatPro widget usually says I have about 10-30 MB of "free memory", which seems low compared to my 2 GB.

So why is my computer slow? RAM? CPU? Something else?
Click to expand...
There's more to it than "free memory":
A better indicator is to look at the System Memory tab on Activity Monitor. Look at your "Page outs" and "Swap used". If those are excessive, you need more RAM.

It's very unlikely that your CPU is the bottleneck.
 
GGJstudios said:
You need more RAM.
Click to expand...

Ok. Thanks. That helps.

Can I ask why my computer now is slow, when a year ago it was nice and zippy? I had the same configuration then as now. I'm usually content to chalk this up to my computer getting old and tired, but I guess I'd be interested to know if there's a reason.
 
itom37 said:
Ok. Thanks. That helps.

Can I ask why my computer now is slow, when a year ago it was nice and zippy? I had the same configuration then as now. I'm usually content to chalk this up to my computer getting old and tired, but I guess I'd be interested to know if there's a reason.
Click to expand...
It depends on what apps/processes and widgets you have running. Also, if you're running low on disk space and paging a lot, that can bring your performance to a halt. Take a look at Activity Monitor, selecting "All Processes" at the top instead of "My Processes". Sort them in descending order by CPU, RSIZE and VSIZE to get an idea of what processes are consuming system resources.
 
What is considered a "good" ratio of page ins to page outs?

I noticed on my iBook G3 the other night, they were almost even with each other, which I assume is way too many page outs! (No big surprise at 640mb RAM, maxed out.)

Now on my 2010 MBP 13", just surfing mostly but with a goodly number of tabs, it's 631,000 page ins to 104 page outs. That's probably fine.

But this made me wonder: At what ratio of "ins" to "outs" do you decide that you have a RAM bottleneck?

Thanks,
Miss Terri
 
Miss Terri said:
What is considered a "good" ratio of page ins to page outs?
Click to expand...
Page ins aren't important when determining paging issues. It's only page outs. A ratio isn't important.
Page ins / Page outs

This refers to the amount of information moved between RAM and the hard disk. This number is a cumulative amount of data that Mac OS X has moved between RAM and disk space.

Tip: Page outs occur when your Mac has to write information from RAM to the hard drive (because RAM is full). Adding more RAM may reduce page outs.
Click to expand...
 
Last edited:
GGJstudios said:
Page ins aren't important when determining paging issues. It's only page outs. A ratio isn't important.
Click to expand...

Okay, thanks. Then I guess my question is actually "How many page outs would constitute a RAM bottleneck?"

And is it over a certain period of time that you count them?

I just would like an idea if 200 is a lot? 2,000? More? I'd like to be able to interpret the numbers for my own machine.

Thanks,
Miss Terri
 
Miss Terri said:
Okay, thanks. Then I guess my question is actually "How many page outs would constitute a RAM bottleneck?"

And is it over a certain period of time that you count them?
Click to expand...
The page outs aren't expressed or measured as a count of paging events, but rather as a total amount of memory in KB/MB/GB that has been paged out. The swap used indicates how big your swapfile on your HD is. If it's 5-10MB, it's not enough to worry about. If it's hundreds of MB or GBs, you likely need more RAM.
 
you also might want to do a reformat (archive and install) to get rid of disk fragmentation.
 
GGJstudios said:
The page outs aren't expressed or measured as a count of paging events, but rather as a total amount of memory in KB/MB/GB that has been paged out. The swap used indicates how big your swapfile on your HD is. If it's 5-10MB, it's not enough to worry about. If it's hundreds of MB or GBs, you likely need more RAM.
Click to expand...

Ah, okay, thanks for the info! I was thinking that, say, "104" was a number of "pages" but I guess it is either kb, mb, or gb (oddly I can't see where the units are listed on iStat).
 
Miss Terri said:
Ah, okay, thanks for the info! I was thinking that, say, "104" was a number of "pages" but I guess it is either kb, mb, or gb (oddly I can't see where the units are listed on iStat).
Click to expand...
You'll see the units expressed on Activity Monitor's System Memory tab at the bottom.
toxic said:
sure, but that doesn't change the fact that a fresh hard drive is faster than an old one.
Click to expand...
For most Mac OS X users, there is absolutely no measurable performance benefit to defragmenting a hard drive. Pretty much the only time defrag helps is in partitioning.
 
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