More RAM doesn't always amount to better performance

Hi all
Reading these threads a lot I get the impression that a great many people think that simply by adding more RAM on a computer will automatically improve the performance.

This is not necessarily true as there are many many factors that need to be taken into account.

The amount of REAL RAM allocated by the OS is based on very complex algorithims and not purely on the size of the application being run. For example I might have a HUGE powerpoint presentation (say 50 MB -- a lot for a powerpoint demo) but the actual REAL RAM needed is of the order of a few KB (yes Kilobytes).

Most applications (possibly Photoshop is one of the rare exceptions) do not need to be 100% loaded into RAM while working. Only the amount of real data "pages" need to be accessed at any one time. The amount will obviously dependon what the application is doing , other processes etc etc.

For example in the power point example as above the data has to be transferred to a Video display -- whilst this is being done the next "slice" of data can be read from the "paging" disk.

Applications which wait a lot on input from the User (such as word processing) can use actually a very small amount of RAM since the keyboard input is far far slower than any DISK I/O required to get data from paging into real RAM.

So before you go "buying huge amounts of RAM" think what you actually need.

For a lot of people better graphics, faster CPU and above all FASTER DISKS might make for a snappier system than increasing the amount of RAM once you've got a reasonable base amount installed.

An 8GB RAM system with very slow disks and poor graphics is often far more frustrating to use than a 3GB machine with lightning fast disks and a decent graphic card irrespective of the CPU installed .

I would hazard a bet here that the biggest bottleneck in 99.9% of home systems is not RAM or graphic card but poor DISKS.

Cheers
jimbo

This is false... :) The amount of VMemory allocated to each program is 4 gigs on a 32 bit system. The amount actually in the RAM can be super small yes. Yes the Disk is possibly the biggest bottleneck, but your title makes it seem like more ram can be worse, where in all reality it won't ever hurt. If you have a crappy hard disk, disable your page file, buy 4 gigs of ram and run completely off ram, this will stop page faults (swapping of memory to the hard drive and vice versa) which is a huge performance gainer...

When it comes to games, Graphics cards are your bigger bottleneck, due to the fact that most of your textures etc are loaded into memory. And if you only have a little RAM then your OS is going to be forced to swap memory in and out of the page file, which will really kill you if you have a crappy hard drive, but if you are playing Crysis, more ram and a kick a video card are a way bigger factor than a fast or slow hard drive.

If you aren't a gamer and your machine sucks, get a core 2 duo or better, with a decent hard drive and a ton of RAM :P

And, it's easier to upgrade ram than say a CPU, also generally more cost effective, but unless you are someone who does some major video editing you probably won't get any performance boost above 2-4 gigs.

lol philosophy from an aussie

if you use ramdisk, or just turn off pagefile, then i think you get lots of performance...HDD is the bottleneck in most cases, but SATA2 is bringing highspeed IO to homeusers

damoh said:

LOL ive just bought 4 gig ram, hope it helps me lol

Hey good news M8 sure you will notice the improvement and be able to go 64X = yeah!

Dont wish to (ram) it home but I find the four gig handy do a lot of burning of films and editing etc ... yes a lot of burning indeed recently :)

baarod said:

I think this discussion needs to take into account the application's ratio of locked or non-pageable memory to it's working set. More memory will prevent commit paging of memory marked as pageable even if it is allocated in the virtual heap. The metric you really need to look at is hard page faults, that is, when memory has been allocated as pageable but insufficient physical memory conditions have caused those pages to be committed to the page file and purged from physical memory. A hard page fault occurs when that memory is accessed and has to be reloaded from the page file back into memory. That's where performance is impacted. So, more memory is almost always better!

Yes, this calls for a chart... I tried to update the chart to today's prices, but you'll notice when you hit between ram and hard drive the hit cost is tremendous, it goes from 30 nanoseconds to 8 milliseconds! That is a terrible time loss in the computer world... (for those who don't quite understand that, the cost to hit the hard drive over ram is 266,666 times slower!)