Used And Free Swap Space? What Is It Exactly?

[fommof]

Hi, i've been using the logging feature of AIDA64 quite a bit.

I still haven't figured out what exactly is the Used/Free Swap space...

It's not the virtual memory/page file for sure because i always set this manually and it's always fixed (usually either 2000MB or 4000MB depending on the pc) and the sun of the reported free and used swap space don't agree with my virtual memory/age file.

So, could you please explain to me what the Swap space is?

Thanks in advance.

[Fiery]

AIDA64 uses the industry standard GlobalMemoryStatusEx Windows API call to detect memory status. That function returns a structure called MEMORYSTATUSEX. The swap space info is taken from the structure entries called ullTotalPageFile and ullAvailPageFile. You can read about their meaning and purpose at:

http://msdn.microsoft.com/en-us/library/windows/desktop/aa366770(v=vs.85).aspx

Regards,

Fiery

[Squall Leonhart]

Swap is the total virtual memory available and used in the system.

This is the totals of the System ram and Paging files all up.

[MegaZX30]

Hello,

sorry to revive an old topic, I was googling and this popped up...

But if anyone is will answer i would like more clarity on this issue myself.

If the Swap Space is total virtual memory (Page + Physical RAM)

how can Virtual Memory itself be larger?

Win 7 Home Premium

Aida reports (on my system of course, lol)

Total RAM avialable: 8140MB

Used: 1806MB

Swap Space Avialable: 11210MB

Used: 1898MB

Virtual Memory: 19351MB

Used: 3611MB

Page File: 3072MB

Current / Peak: 0MB / 0MB

If whats said is true 'Swap Space = virtual memory' this makes no sense to me...

(Random Other Note: May reduce or disable Page file altogher in the future a: really don't need that much page file b: want to perserve max write life on my SSD)

[Squall Leonhart]

iirc, Virtual counts all memory used by all processes all up, but applications using shareable addresses are not discounted so the virtual count will appear to be larger than the swap.

the Swap space is the total available / in use memory from Physical + Page

The page file is infact not doing anything on that drive and the access patterns for the page file aren't damaging to an SSD in any case.

basically, its there if its needed and sometimes, it really is needed

[MegaZX30]

Oh thank you, I think i understand better now how and why that apears to be about twice the size of the swap space file now.

The page file showed up as 0MB in use as I had just freshly booted my computer, i know certain programs do automaticly start using it though. Accordingly the other night it was using about 300MB in total don't know what the max usage has been though.

I know space is reserved for the page file but i thought it was like 'blank space' so when fresh data is wrote to it would be writting to a cell of the ssd and then eventually deleted again when freed up for new use?

[Squall Leonhart]

Yes, but thanks to wear leveling, page file activity doesnt degrade an ssd any faster than writing to profile dat files (and this happens more often xD)

[MegaZX30]

Oh alright i see, this is my first build with a SSD and i've been slightly out of the loop information wise with modern & current PC tech.

(Prev. computer build dated by oh i would say at least 10 years if not longer... lol, Pentium 4 s478 with AGP cards so quite the jump with current pc tech)

Thank you for your input it cleared up some of my questions.

[tistou77]

I have 8GB of RAM and virtual memory is disabled, and I have it with AIDA64

[Pill]

I have 8GB of RAM and virtual memory is disabled, and I have it with AIDA64

Yep same here.

I have 8GB ram installed with no page file, yet AIDA reports my total virtual address space as 16GB....

[Squall Leonhart]

i'll have to research this further, unless fiery wants to post a link to the relevant article

 

Virtual Address total has nothing to do with the pagefile.
You  can map 64GB on a system that has 16, with no page file, but if you try to utilise memory exceeding 16GB you will crash the system.

[Fiery]

i'll have to research this further, unless fiery wants to post a link to the relevant article

Windows kernel's memory management is a mystery, so I personally would be interested to read a proper article that explains all those -- seemingly -- anomalies. AIDA64 reports what Windows kernel reports, so if you guys reckon those values don't add up, then it's only Windows kernel to blame or inquire

[Squall Leonhart]

Follow up post since others are reading this

"Commit Size" is titled "Page File" in windows XP/9x and certain utilities made by a Unwinder, but it does not reflect the amount of of actual on-disk page file in use.

[sunilmedapati3]

Swap space in Linux is used when the amount of physical memory (RAM) is full. If the system needs more memory resources and the RAM is full, inactive pages in memory are moved to the swap space. While swap space can help machines with a small amount of RAM, it should not be considered a replacement for more RAM. Swap space is located on hard drives, which have a slower access time than physical memory.