Always Under My Peak Commit Charge. . .

[Dancali]

This board has people that seem to be able to help with just about any computer question so I'll throw this one out. . .

I have this neat new laptop (Thinkpad 1.8 pentium centrino) but the bottleneck is definitely the 7200 rpm hard drive. My desktop features the 10,000 sata raptor hard drive to help with having to load lots of database information.

I have 512 mb ram and the peak commit charge essentially never goes over about 400 mb.

My understanding of what's going on could be completely off but here's what seems to be the situation: Once a program is loaded my laptop works with it quickly. But if I keep it in the background for a while (program still open) it seems to be written back to the hard drive so that when I manipulate it again it lags until it goes back into ram.

Does this sound right? Is this how a computer normally handles data?

Now, if I were to have, say, 1gb or 2 gb of ram, would the computer write to the hard drive less and just keep more information in ram? Or would my ram usage stay the same since, anyway, my commit charge never even approaches the 512mb ram I have in there right now?

Thanks.

[waldwolf]

Dancali - Its doubtful additional RAM (memory) would noticeably speedup your system, unless your involved in very heavy CAD or video processing.

First, it's difficult to answer your question(s) without having specifics about BOTH computers, (make/model number/processors/etc., etc.).

Are you sure your IBM Thinkpad laptop has a 7200rpm HDD? Most laptop HDD's operate in the 4200-5200 range. Also, what is the buffer size, if any. 2mb? 8mb? What is your HDD's access time?

Frankly, trying to compare your desktops Western Digital "Raptor" 10,000 rpm SATA, 8mb buffer, 4.5ms access time drive to a 4200 rpm EIDE, 2mb buffer, 12ms access time drive is, well, like comparing apples to oranges. Your desktop will run rings around your laptop every time. (For example, a 7200 rpm E-IDE HDD will improve access time 33-40%, vs. a 5200 rpm E-IDE HDD)

Windows does utilize two (2) of its own HDD cache methods called VCache for DISK and FILE settings. They can (with patience) be re-adjusted to improve performance, however, unless your very experenced in computer & software operation, it is recommended you allow Windows to manage these settings.

Hope this helps.

[Firefoxx]

A 2.5" laptop harddisk will be slower than a 3.5" desktop harddisk spinning at the same rate. A matter of physics, so you're always going to be slower. It's a tradeoff for using a notebook.

I have 1GB of ram, and my commit charge never goes above 850MB. The more memory you have, the more programs that can fit in, and the more that can be used for cache. If you are using memory-intensive database programs, then of course adding more ram will help.

What you think about how windows handles ram management is sort of correct, although it can be more complicated than that. Having more ram does solve some of the virtual memory usage problem. But it really depends on more than that.

If you have gobs of ram (1-2GB, depending on the apps you use) you could conceivably set your virtual memory to the minimum allowed (2mb?). In that scenario, you wouldn't get any lag for loaded programs, since any they can't be written out to the harddisk.

[autonomous_unit]

...

My understanding of what's going on could be completely off but here's what seems to be the situation:  Once a program is loaded my laptop works with it quickly.  But if I keep it in the background for a while (program still open) it seems to be written back to the hard drive so that when I manipulate it again it lags until it goes back into ram.

Does this sound right?  Is this how a computer normally handles data?

<{POST_SNAPBACK}>

Yes, the OS is always balancing the use of RAM for holding: actual process data, e.g. a modified word doc, undo levels, and screen image; buffers, e.g. in progress reads/writes to disk or network; and regular disk cache, e.g. file data that has been accessed before and might be accessed again. Adding more RAM gives it a bigger playground but does not necessarily solve the problem of a poor balance.

Running Linux on laptops, I found that having more RAM (1 GB) and explicitly turning off virtual memory helps my typical case. This keeps things like mozilla, editors, and terminal screens from getting swapped out and lagging whenever I go back and forth to different windows etc., and it also allows the harddrive spin down for hours at a time.

In this case, the OS does not have the choice of putting process data to disk when it wants to keep more buffers or cache. So, I am favoring programs with which I interact at the expense of even slower access to disk files. However, the risk is that I forget to reenable it and I run out of memory if I happen to start complex digital camera image editing etc. or leave mozilla running for a week or two (it slowly grows over time).

Slower disk access is just one of the unavoidable tradeoffs of using a laptop... although I suppose you could get an external USB2 drive cabinent and put the fastest desktop disk you can find in it. Or even one of those external RAID enclosures and run it in striped (non-redundant) mode!

[slimdog]

Hi Dancali

Your understanding of how a computer handles data is basically correct, and yes increasing the amount of RAM could solve some of your problems. However before you go to the time and expense of going that route, it's always worthwhile looking at other options. Too often people go for the complicated (and usually expensive) options before looking at the simple (and usually free) ones.

Before you do anything you should find out what is running at start-up on your computer, and then stop them. You will normally get a good idea by how many icons you have in your task bar and how long it takes for the computer to boot up, then ask the question, "Do I really need that program running all the time"

Software writers ALL think that their programs are indispensable and set as default that they run on start-up. It doesn't take long for your computer to slow down to a trickle.

What is called "Good House-keeping" can have a major impact on how a system functions

[Dancali]

Thanks for all the input guys.

waldwolf: It really is the 7200 rpm Hitachi travelstar. I gave them 3,000 baht extra to upgrade to this drive. Here are the system specs for each:

IBM Thinkpad R51

1.8 Pentium M Dothan

512 mb pc2700 ddr ram

7200 rpm 60 gb hard drive

32 mb video card

Desktop:

Pentium 2.8c

ASUS p4p800se mb

512 mb dual channel pc3200 ddr ram

10,000 rpm 74 gb raptor hard drive

64 mb radeon 9200

Much to my happy surprise, the notebook is actually slightly faster than my desktop in many areas (probably do to too much background crap running on my desktop). I set up the two systems side by side and tested various operations. The only area where there's a difference is when doing hard drive intensive stuff, and even then it's manageable.

Firefoxx: If I had 1 gb of ram, would it change the commit charge in my system at all, or would my computer still stick with the same usual of maybe 300 mb usual with a peak of 400 mb?

autonomous_unit: Hmm, the idea of adding ram and reconfiguring the os to write much less to the hd sounds good.

slimdog: This is a brand new computer so the amount of background junk on this computer is not a big concern. But on my desktop, I need to do some serious cleaning up. Also, IBM does prepackage quite a few applications which I haven't goen through completely to figure out what is just a waste.

The more I use my notebook and set it up to replace my desktop, the less I see performance problems.

I think I'll play around with the idea mentioned here by multiple people about limiting hard drive writing. Could somebody tell me exactly how to do this, or point me to a good link? Also, is the only thing to watch out for going over the 512 mb of ram and getting a memory error? Any serious things I should watch out for?

Thanks,

Daniel

[Firefoxx]

According to most guides, if your peak commit charge (the highest amount of memory actually used for programs, applications, and sytem) doesn't exceed physical memory, then you don't need to increase your ram.

However, if you want get rid of most of the paging that you mentioned, then it might be possible to do as I said: Upgrade to 1GB and reduce the virtual memory size to minimum. Since your peak commit charge is only 400+MB, it's doubtful that you'll run into any problems. You do this by going into my computer, properties, advanced, performance settings, advanced, change, custom size (few megs, same value for both, minimum value is shown at the bottom), set.

A 1.8 Dothan is faster than a 2.8 P4, since a P4's ghz numbers are pretty inflated.