?? PagePool ??

[gguruusa]

no, it's not RAM you gain (RAM is program memory). Swapfile space is not nearly as usefull as actual RAM is, but it does let you run more processes than you could if you didn't have it. Think of it as a cache for memory occupied by the executable portions of programs.

[cheesegrater]

"The Page Pool
Applications use RAM in two ways. There is code that runs, and there is data that is created while it is running. On a NOR device, the code can run directly from the ROM and not be loaded into RAM first. This process is called XIP (eXecute In Place). NAND devices can't XIP, so their code is loaded into RAM and executed from there. If you don't have a Page Pool, this code is loaded into normal RAM. The Page Pool is a mechanism to limit how much code is loaded into normal RAM. With a Page Pool, we can unload code that hasn't been used in a while and reload it later if we need to. We can't do that without a Page Pool.

On a typical NAND-based WM5 device, the Page Pool is 4.5M."

this quote was taken from: http://blogs.msdn.com/windowsmobile/...17/494177.aspx

i thought it was a pretty good explanation. if you're curious the article gets into the dma buffer, radio stack etc., and how they affect device memory.

i've always thought of the page pool in wm to be comparable to the swap partition on a linux system, or virtual memory in windows. please set me straight if i'm crooked.
hope it helps.

[gguruusa]

Originally Posted by Success100

id like to chime in on this as well..are you suggestin that adjusting the page pool is allocating storage memory to program memory?? that doesnt seem right, if we could do that, our RAM worries would be non-existent..and thats definately NOT how it currently is..

Sort of, but not quite. Pagepool is virtual memory, but, unlike RAM (which you can write to an unlimited number of times), we're on a flash device (with limited wite cycles) so the pagepool can only contain code sections - no data sections. Plus, you have to have your program "paged in" to run, so a program can't ever access more RAM than you pysically have (because no data sections are allowed in the page pool). Since we can only page a portion of whats in RAM (just the code sections), RAM can quickly be consume by data sections.

There's always a price to pay, too. The larger the pagepool, the more storage space you consume (obviously, cause that's where it's stored), and you lose a small amount of RAM to track what's in the pagepool and where it is. And, of course, if you actually have to page something in, that's not nearly as fast as it already being in RAM.

So, if you find yourself running out of RAM, can increasing pagepool help? Definitely maybe. If you have lots of code sections, increasing pagepool might help. Once you've increased pagepool to a certain point, it won't help at all and will only hurt. That point is dependent on the nature of the software you run, and therefore will vary from user to user.

Will increasing/decreasing pagepool speed up your device? Definitely maybe. It all depends on why it's slow in the first place. Generally, you will only notice pagepool effects when swapping tasks. How often that occurs and whether you think it's better/worse depends on the nature of the software you run, and therefor will vary from user to user.

Will increasing/decreasing pagepool make my device more stable? Increasing pagepool should make your device feel more stable (mainly because programs are being swapped instead of forcibly closed). The only time decreasing pagepool helps stability is when you have really piss poor drivers (which, since we're stealing bits and pieces from other devices, may in fact be the case with any give kitchen/ROM).

[Perasite]

Again, gguruusa, brilliant analysis. Thank you for the explanation. Now I know I want a new phone with more program memory

[cheesegrater]

gguruusa, awesome. you put it best. appreciate the time you took to type that mess up. it's extremely helpful.

[robmayer]

Great explanation, very helpful!

[Fresh2Death]

gogo gguruusa!!

[bitbrat]

OK, so I have tried 7, 4, and 8 on a new 6.1 ROM and I am having horrible problems, so I guess I have other issues....

Freezing/locking and very slooooooow response times, very erratic battery consumption figures etc.


Back to the kitchen - I need a new mixer!

[bzxzlg]

Originally Posted by bitbrat

OK, so I have tried 7, 4, and 8 on a new 6.1 ROM and I am having horrible problems, so I guess I have other issues....

Freezing/locking and very slooooooow response times, very erratic battery consumption figures etc.


Back to the kitchen - I need a new mixer!

Someone in the 6.1 postings wondered if their ROM size was "pushing the limit" (http://forum.ppcgeeks.com/showthread...ize#post224224). Their selections were small enough to cook and load on the PPC, but they got bad response. I had kinda noticed that as well myself, so now I've got a ROM that works. I use the default pagepool of the cooker.

Cheers

[boggsie]

Originally Posted by gguruusa

Pagepool is virtual memory, but, unlike RAM (which you can write to an unlimited number of times), we're on a flash device (with limited wite cycles) so the pagepool can only contain code sections - no data sections.

<snip>

The larger the pagepool, the more storage space you consume, and you lose a small amount of RAM to track what's in the pagepool and where it is.

<snip>

So, if you find yourself running out of RAM, can increasing pagepool help? Definitely maybe.

<snip>

Will increasing/decreasing pagepool speed up your device? Definitely maybe.

Remarkably clear explanation ... great post. My thanks.