How much RAM does iOS or iPadOS use on boot up?

[Bubble99]

I will like to know how much RAM is being used by the OS on boot up. My guess is iOS or iPadOS is using 1 GB of RAM on boot up now days if Android, Linux and Windows tablets and phones are using 1 to 2 GB just for OS on boot up.

This means an iPad with only 3 GB RAM if say 1 GB is being used for the OS than you only have 2 GB left for apps. So one or two app running may be okay but running many apps in background would be refreshing the apps lot.

So if you have say a web browser open with 10 tabs and two or three apps running in the background the iPad will be refreshing lot more with 3 or 4 GB of RAM.

I would be shocked if iOS or the iPadOS uses 512 MB of RAM on boot up for the OS today base on Android, Linux and Windows using 1 to 2 GB now days.

And Firefox on the desktop computer with 10 tabs open is like 3 to 4 GB of RAM just for Firefox alone looking at windows task manger. So mobile app may be like 1 to 2 GB with 10 tabs open.

 

[Sheepish-Lord]

That's not how RAM works, suggest researching memory management.

 

[Slartibart]

I would guess that this is a.) somewhat dynamic, b.) might for iOS/iPadOS depend on the total available RAM and c.) number of e.g. widgets, services etc.you run on startup, and, well, iOS/iPadOS version used.

For what’s worth: an 2020 11” iPP reports roughly 50% available after a cold start of iPadOS 16.3beta.
Does it mean anything for my usage? = e.g. modest amount of open tabs in Safari (~5; depends of course on the site), streaming music in Apple Music to a stereo, while stitching panos from RAW photos in Affinity Photo(e.g. 14 20MP photos) - No.

Panos get stitched, music plays without hickups, switching to Safari… runs as fluid as it can get.
Similar to other scenarios where apps running in splitview while playing PiP-video and copying data to, between or from local or remote devices/server.
If there is a perceivable impact for me as a user it seems to depend on the particular app e.g. Amazon Photos does neither support splitview nor background upload - in 2022!

Another example: yes, in any of the above scenarios more RAM could result in less reloads of pages in Safari - especially when not using an adblocker, having multiple pages open, bring it from the background to the foreground or switching between pages - but again: in my experience most perceivable impacts are not depending on RAM but the implementation of a particular implementation in an app - on the same iPad you can easily load and edit one of said panos with e.g. a dimension of 23000x6800 pixels in Affinity Photo 1&2, RawPower or even Apple’s Photos, Pixelmator Photo will not open it… seems not depend on the available RAM/RAM occupied by OS is my educated guess here. 😁

There is clearly nothing to “be shocked” about RAM usage of the operating system on… probably any decent platform/OS, isn’t it? As what kind of an indicator serves that for in your opinion?

nota bene: the 7&8th generation iPads on iPadOS 14/15 I administer at a school, as well some last generation iPPs on iPadOS 16 report (much) more than 50% of RAM available after a cold start.

 

[Bubble99]

That's not how RAM works, suggest researching memory management.

As computer tech who fixes computer on windows and fix my own computer problems on Windows and Linux I know how RAM works.

Well put 4 GB of RAM in a desktop computer running bloated Linux desktop environment and run top or htop in the terminal with Firefox running with 30 tabs and watch computer run slow accessing the SATA HDD swap file.

And no no no no no no no, in Windows, Unix , BSD and Linux don’t purge running process or daemons. You are not running VM, nano or emacs than open up Browser like Firefox or Pale-Moon browser with 20 tabs open than switch back and every thing you typed is gone because your auto save did not take place fast enough on iOS or iPadOS.

Now get job at Best Buy at Geek Squad because you know nothing on how computers work.

As some one who has two iPads I tell you with a fact the iPad with more RAM refreshes apps much less than iPad with less RAM that can hardly run more than two background apps.

The iOS and iPadOS has no swap file like Windows, Linux, Unix or BSD OS.

If you have 3 GB of RAM on the iPad and run lots of stuff the OS will start purging running apps in background. My iPad with more RAM can run way more stuff in the background with out refreshing. And refreshing is not problem on traditional OSs.

Well the average user may only run only one or two apps in the background, I run many apps in background on the iPad and switch back and forth running apps and iPad I have with more RAM well refreshes less.

There nothing frustrating typing reply in a messages forum and I have to check other app very fast and come back to find page reloads again and thankfully the iPad with more RAM does this less.

I know how Windows and Linux works on boot up as all RAM is not going to OS.

On Linux on boot up it uses 1 GB on most new desktop environment than the older ones like XFCE and LXDE that uses any where from 300 MB to 700 MB depending on distro that puts all other fluff on top of it.

Windows uses about 2GB but there are debloat scrips that cam bring down to just over 1 GB.

Well Windows 11 takes up more HHD space and RAM than Windows 10 and Windows 7.

I have old desktop computer running windows 7 with 4GB RAM and looking at task manger closing backward tasks I can get it down to 2 GB of RAM. The computer only gets slow when it gets to 90% of RAM usage.

Back in Windows 98 days if all the RAM was used up the computer would crash and there also was memory leaks. That why you need a swap file and the app has to release RAM.

Your Knowledge on what RAM is well is shocking as I have troubleshooted conputer problems when 90% RAM is used and computer gets slow.

You also never worked in 90s when memory leaks where common thing.

 

[Bubble99]

There is clearly nothing to “be shocked” about RAM usage of the operating system on… probably any decent platform/OS, isn’t it? As what kind of an indicator serves that for in your opinion?

nota bene: the 7&8th generation iPads on iPadOS 14/15 I administer at a school, as well some last generation iPPs on iPadOS 16 report (much) more than 50% of RAM available after a cold start.

Well operating systems and software have been getting more and more bloated as years go by.

With Windows sadly being worse, I can only see in 15 years from now where 8GB RAM will not be enough and new computers will be coming with say 64 GB of RAM for average user.

The only people know who need 16 GB RM or 32 GB RAM now are gamers and content creators but that may change in the future. The web is getting more bloated with adds and pictures every where and just bloated websites not to say browser takes up way more RAM today than 10 years ago.

It probably is a good thing there so many iPad out there with 2 GB RAM and 3 GB RAM as if it had 6 GB RAM or more iPadOS will just get more bloated.

I believe the first iPad only had some thing like 512 MB of RAM. But than again the first iPad did not really have multitasking and was not really computer replacement. I think vision of Steve Job at the time is the iPad at time was not PC replacement but a tool for Mac or Windows. Than the idea of PC replacement and multitasking was being added every year after every year.

Well Windows 3.1 and MS DOS in day had major problems and multitasking problems in way it took Microsoft long time before switch to Windows NT to fix many of the problems. And windows 95 and windows 98 did not have good multitasking with errors and crashes and slow computer was common thing.

Well the iPadOS will not be switching to new Kernel it is much more PC like today than it was 5 years ago. And in say 10 years from now laptops may go way of desktop computers.

The only people today I see into desktop tower computers are computer enthusiast or hard core gamers. And people that cannot say goodbye to 90s way of life.

But laptops will probably go way like desktop computers where the future is smartphones and tablets.

And the far far future being AR and VR and chip implants along with AI doing lot of the work where even smartphones and tablets gone in way far future.

 

[Danfango]

Well this thread clearly shows no one understands OS memory management so far.

Firstly you can't compare across architectures at all realistically so there is no rationale between comparing an Intel platform to an ARM platform. You can't even compare across device classes i.e. between macOS and iOS for example.

iOS itself manages application state and therefore memory completely differently to everything else using a lifecycle model. It will transition your apps from foreground -> background -> suspended for memory and energy related events and manage that entirely for you. In a suspended state, only metadata is present in RAM to recover the state. What is persistent in RAM at all times is minimal and very well engineered. The outcome is that there is plenty of RAM left for one or more application contexts sitting around, which is all you need.

It really doesn't really matter how much RAM you have in an iOS device for most tasks. What is more important is how quickly the OS can recover the state when you switch between suspended apps and bring them to the foreground. And that is handled by the absolutely insane storage to CPU bandwidth available on all iOS devices.

For some heavy applications like media processing, something that iOS was admittedly not designed for initially, the larger iOS devices can have up to 16Gb of RAM, larger process sizes and virtual memory, but that's mostly not needed.

Remember that this is all a compromise which is designed to balance RAM requirements, power requirements and user interface concerns. The tradeoff is different on other platforms and devices.

 

[Bubble99]

Well this thread clearly shows no one understands OS memory management so far.

Firstly you can't compare across architectures at all realistically so there is no rationale between comparing an Intel platform to an ARM platform. You can't even compare across device classes i.e. between macOS and iOS for example.

iOS itself manages application state and therefore memory completely differently to everything else using a lifecycle model. It will transition your apps from foreground -> background -> suspended for memory and energy related events and manage that entirely for you. In a suspended state, only metadata is present in RAM to recover the state. What is persistent in RAM at all times is minimal and very well engineered. The outcome is that there is plenty of RAM left for one or more application contexts sitting around, which is all you need.

It really doesn't really matter how much RAM you have in an iOS device for most tasks. What is more important is how quickly the OS can recover the state when you switch between suspended apps and bring them to the foreground. And that is handled by the absolutely insane storage to CPU bandwidth available on all iOS devices.

For some heavy applications like media processing, something that iOS was admittedly not designed for initially, the larger iOS devices can have up to 16Gb of RAM, larger process sizes and virtual memory, but that's mostly not needed.

Remember that this is all a compromise which is designed to balance RAM requirements, power requirements and user interface concerns. The tradeoff is different on other platforms and devices.

There are times I just want to scream when Apple never took the philosophy of traditional OS like Windows and Linux. Where you have browser open with 10 tabs open than switch to other app than switch back and page reloads, this does not happen on traditional OS. On newer computers I can even have 10 youtube videos playing or more and computer does not slow down or crash or spit out errors.

There are times I wish the iPad would give an error saying close program or running out of swap file if Apple took direction like traditional OS and used swap file from get go. I heard new high in iPad pro are going to start using part of SSD as swap file. One guy was showing two videos playing on the iPad pro with stage manager running.

But I can run way more apps on my iPad with more RAM with out app reloading than on my iPad with less RAM.

But I think way iPhone is and iPad if it where like traditional OS that never purge task the experience would be terrible for most home owners.

There are still iPad with 16 GB SSD in used that would be filled up in no time if some one had 40 tabs open and other things in background and never refresh iPad if Apple started to use a swap file for 16 GB SSD iPad.

I know iOS and iPadOS is much less bloated than say most OS and optimize the RAM more but still I find it hard to believe iOS and iPad OS just for OS to run is using less than 1 GB of RAM today when you look at similar prototype tablets running like Linux clones like jingOS and Gnome in fact most new Linux DE are pushing around 1 GB on boot up. There was even time when gnome was getting close to 2 GB of RAM on boot up.

But I find it hard to believe Apple has magic that the OS is way less resource intensive than most OS by lot.

Well yes iOS and iPadOS is less resource intensive than Android, Windows and most new Linux DE but I would be shocked if the OS is using 400 to 700 GB RAM just for the OS to run properly alone and FireFox using 500 MB to 900 MB alone.

Yes mobile app take up less RAM than desktop apps but but it is hard to believe it is using 400 MB to 700 MB of RAM just for OS to function probably.

Well there is a trick I found out with iPadOS if you running say 20 things in the background and you are starting new things like say new tabs opening and just check back to apps you don’t want to reload every 2 to 3 minutes or so and OS seem to put app has higher priority unless you open too much. It works well 80% of the time.

​

 

[unrigestered]

on my iPad with just 2GB of RAM, it will forget the text i'm typing on forums like this after changing to something like the notes app and back before having submitted my post without any other apps running at all.

on iOS devices with more RAM, this won't happen as easily

 

[MajorFubar]

The iOS and iPadOS has no swap file like Windows, Linux, Unix or BSD OS.

It does in iPadOS16.
See, it's OK to take the snooty holier than thou high ground and tell others they know jack sh*t like you are doing, but it only works when you get your own facts right, otherwise you look a pr**k.

 

[Bubble99]

It does in iOS16.
It's OK to have a snooty holier than thou attitude and tell others they know jack sh*t like you are doing, but it only works when you get your own facts right, otherwise you look a pr**k.

This is experience I have using computers not some lay person reading computer book saying A B C D and this how works that not what I have experience and fixing computers.

There is also internet myth going around now that on most forums that the OS loads every thing into RAM that RAM acts as cache that not what I have experience using computers all way back from 90s and troubleshooting computers.

The little bit of cache the RAM has and uses like the CPU cache is mostly for app starting up faster not keeping the entire content. And with SSD being really fast these days the loading of the app and read and write speeds this is less of a problem in todays world than the slow hard drives and floppy drive.

Well it is true MacOS may be doing some thing different now than say the way Windows and Linux does things with RAM. I don’t have Mac computer in front of me so cannot look at it at boot up and doing work and closing and opening apps.

I read reports here that MacOS is using SSD lot these days and members worried the SSD swapping being uses too much and will cause too much read and write cycals for SSD and SSD will die after too many cycles even fact the app or tab was close still lots of SSD reads and write base on people posting. Some members here like to say MacOS likes to keep every thing in RAM and use swap way too much even after closing app.

So may be it is true MacOS is doing some thing different but that is not how windows and Linux does things. And my windows desktop computer running windows 7 when it gets to 90% RAM usage the computer gets slow.

 

[Danfango]

This is experience I have using computers not some lay person reading computer book saying A B C D and this how works that not what I have experience and fixing computers.

There is also internet myth going around now that on most forums that the OS loads every thing into RAM that RAM acts as cache that not what I have experience using computers all way back from 90s and troubleshooting computers.

The little bit of cache the RAM has and uses like the CPU cache is mostly for app starting up faster not keeping the entire content. And with SSD being really fast these days the loading of the app and read and write speeds this is less of a problem in todays world than the slow hard drives and floppy drive.

Well it is true MacOS may be doing some thing different now than say the way Windows and Linux does things with RAM. I don’t have Mac computer in front of me so cannot look at it at boot up and doing work and closing and opening apps.

I read reports here that MacOS is using SSD lot these days and members worried the SSD swapping being uses too much and will cause too much read and write cycals for SSD and SSD will die after too many cycles even fact the app or tab was close still lots SSD reads and write base on people posting. Some members here that like say MacOS like keep every thing in RAM and use swap way too much even after closing app.

So may be it is true MacOS is doing some thing different but that is mot how windows and Linux does things. And my windows desktop computer running windows 7 when it gets to 90% RAM usage the computer gets slow.

Your experience is wrong. Some of use actually wrote bits of the things you are talking about.

There is no myth that stuff is loaded into RAM. It is true. RAM is used as a cache. Every since we got virtual memory systems back in the 1970s we have had RAM cache for block based filesystems. The kernel memory manager, regardless of the OS trades this off against process heap allocation. That is true of windows, Darwin, Linux, BSD, everything. The whole of computing infrastructure is a cache heirarchy:

CPU registers -> L1 cache -> L2 cache -> L3 cache -> RAM -> disk -> network

SSD swapping is unlikely to be a long term issue. The only time, in my somewhat vast experience, that this has been an issue was on SLC SSDs used in enterprise database servers. And they still lasted 2+ years of sinking an order of magnitude writes more than they were specified. I just ran smartctl on my now year old MBP which is used heavily as a development workstation and it's showing 9TBW and 0% usage.

Windows gets slow when it hits 90% of RAM because NTFS sucks. The MFT causes block and cache contention on small exclusive reads writes which means it can't keep the entire MFT in cache and hit the pagefile at the same time efficiently. So it has to keep going back to the disk with lots of fragmented reads and writes resulting in IO contention and therefore aggregate latency. This doesn't happen on Linux as the filesystem access model is optimistic, non blocking and the filesystem is far more efficient. Same cause as when you check out a 1Gbyte git repo on a windows machine it takes 24x as long as the same hardware as a Linux machine.

 

[Danfango]

on my iPad with just 2GB of RAM, it will forget the text i'm typing on forums like this after changing to something like the notes app and back before having submitted my post without any other apps running at all.

on iOS devices with more RAM, this won't happen as easily

Yes that's a big problem. This should not happen if the app was architected correctly and recovered all the state after it was suspended. It should appear exactly how you left it. Same with browser tabs.

However as the browser engines were never architected with that in mind, all bets are off.

 

[Bubble99]

Your experience is wrong. Some of use actually wrote bits of the things you are talking about.

There is no myth that stuff is loaded into RAM. It is true. RAM is used as a cache. Every since we got virtual memory systems back in the 1970s we have had RAM cache for block based filesystems. The kernel memory manager, regardless of the OS trades this off against process heap allocation. That is true of windows, Darwin, Linux, BSD, everything. The whole of computing infrastructure is a cache heirarchy:

CPU registers -> L1 cache -> L2 cache -> L3 cache -> RAM -> disk -> network

SSD swapping is unlikely to be a long term issue. The only time, in my somewhat vast experience, that this has been an issue was on SLC SSDs used in enterprise database servers. And they still lasted 2+ years of sinking an order of magnitude writes more than they were specified. I just ran smartctl on my now year old MBP which is used heavily as a development workstation and it's showing 9TBW and 0% usage.

Windows gets slow when it hits 90% of RAM because NTFS sucks. The MFT causes block and cache contention on small exclusive reads writes which means it can't keep the entire MFT in cache and hit the pagefile at the same time efficiently. So it has to keep going back to the disk with lots of fragmented reads and writes resulting in IO contention and therefore aggregate latency. This doesn't happen on Linux as the filesystem access model is optimistic, non blocking and the filesystem is far more efficient. Same cause as when you check out a 1Gbyte git repo on a windows machine it takes 24x as long as the same hardware as a Linux machine.

So explain to me why when there is Windows or Linux and lots of apps loading yes lots apps and RAM shows 5 GB RAM used and when you close it it well goes way down is my eyes than lying to me? Looking at task manger or htop?

 

[Bubble99]

Your experience is wrong. Some of use actually wrote bits of the things you are talking about.

cache heirarchy:

CPU registers -> L1 cache -> L2 cache -> L3 cache -> RAM -> disk -> network

Yes that true but cache is well less problem toady than in old days with very slow hard drives when the RAM gets filled up to 100% used with apps and stuff running and computer starts to use swap file. If you worked on computers in 90s and 2000s you don’t want use swap and would close apps when gets close to full looking at status RAM usage.

Most cache is for operations and calculations not keeping the entire content. The SSD are so fast that apps load in less of second or two these days. The computer boots up in seconds now not minutes.

The SSD are very fast these days that there is little load time starting app these days.

 

[Danfango]

So explain to me why when there is Windows or Linux and lots of apps loading yes lots apps and RAM shows 5 GB RAM used and when you close it it well goes way down is my eyes than lying to me? Looking at task manger or htop?

Yes processes will allocate memory. I would expect them to do so otherwise they won't be much use.

The original point was about iOS which works differently due to the app lifecycle.

Also worth pointing out that what you see in htop and task manager will require some understanding of exactly what the terms mean. There isn't a "I used this amount of RAM" metric. The virtual memory manager complicates what that means. For example in a piece of software I wrote, I allocate 256Gb of RAM on a 16-32Gb machine for a sparse data structure but the total VIRT shows up as the number of pages I have used. I'm using 260Gb of RAM on that machine apparently! I'm not - I'm only using various non-contiguous bits of the 256Gb allocation.

 

[Danfango]

Yes that true but cache is well less problem toady than in old days with very slow hard drives when the RAM gets filled up to 100% used with apps and stuff running and computer starts to use swap file. If you worked on computers in 90s and 2000s you don’t want use swap and would close apps when gets close to full looking at status RAM usage.

Most cache is for operations and calculations not keeping the entire content. The SSD are so fast that apps load in less of second or two these days. The computer boots up in seconds now minutes.

The SSD are very fast these days that there little load time starting app these days.

It's still a big problem. SSDs are still nowhere near as fast as the processors and the network is still painful. We need that cache hierarchy. Processors without data are slow.

Program and OS startup is mostly irrelevant. It always was, even back in the days of big unix machinea (showing my age now). IO and RAM access when the programs are running are what is important. Consider that you can now edit a bunch of 4k streams on an iPad. It doesn't matter how long iOS takes to boot or LumaFusion takes to start.

 

[Bubble99]

Yes that's a big problem. This should not happen if the app was architected correctly and recovered all the state after it was suspended. It should appear exactly how you left it. Same with browser tabs.

However as the browser engines were never architected with that in mind, all bets are off.

There are many threads here on macrumors of members here complaining that the 2 GB and 3 GB iPad reload the apps way more than iPad with more RAM. You think you have 30 tabs open and have music playing and have weather app and and video playing and by magic the iPadOS will not refresh or reload page with 2 GB or 3 GB RAM?

 

[Danfango]

There are many threads here on macrumors of members here complaining that the 2 GB and 3 GB iPad reload the apps way more than iPad with more RAM. You think you have 30 tabs open and have music playing and have weather app and and video playing and by magic the iPadOS will not refresh or reload page with 2 GB or 3 GB RAM?

Well they will. The amount of backgrounded apps is higher the more RAM you have. The killer transition is moving from backgrounded to suspended. Developers (and that includes Safari developers) aren't doing a good job of managing that.

Incidentally my iPad has 8Gb of RAM and doesn't do that.

 

[Bubble99]

It's still a big problem. SSDs are still nowhere near as fast as the processors and the network is still painful. We need that cache hierarchy. Processors without data are slow.

Program and OS startup is mostly irrelevant. It always was, even back in the days of big unix machinea (showing my age now). IO and RAM access when the programs are running are what is important. Consider that you can now edit a bunch of 4k streams on an iPad. It doesn't matter how long iOS takes to boot or LumaFusion takes to start.

May be for semi professional or professionals or like jobs in work environment like CAD or Hollywood work that call for it but for average user apps load very fast at first start up today. And these are even big apps like Microsoft Office, OnlyOffice, LibraOffice and photoshop and GIP start up very fast these days.

 

[Bubble99]

It's still a big problem. SSDs are still nowhere near as fast as the processors and the network is still painful. We need that cache hierarchy. Processors without data are slow.

Program and OS startup is mostly irrelevant. It always was, even back in the days of big unix machinea (showing my age now). IO and RAM access when the programs are running are what is important. Consider that you can now edit a bunch of 4k streams on an iPad. It doesn't matter how long iOS takes to boot or LumaFusion takes to start.

Before SSD windows was well painfully slow at starting up and loading apps being windows OS being bloated yes even on clean install of windows and worse after two or three years of use took long time. In way before SSD windows 95 and windows 98 was faster at starting up than windows 7 and windows 10 using hard drive because of less bloat. The only time Windows 95 and windows 98 was pain is installing software that took very long time and even starting up some bigger programs took long time. But starting up computer on windows is painfully slow using hard drive and laptop starting app for first time takes long time.

Now I would never go back hard drive now and old days of slow accessing slow floppy drive.

Not saying cache hierarchy has go away but for the average user it is less issue than in past with slow hard drive and floppy drive.

 

[Bubble99]

Okay so today I have done an experiment on the iPad, I open the weather app than switched to dropbox and Box cloud app than switched back to weather app and the weather app did not reload than I switched to cloud app and it did load.But only had three apps running.

The experiment two I than open cloud app than open weather app than switched back to cloud app and again did not reload, but this type I than closed he cloud app and switched to weather app and I again because the weather app I did not close it well did not reloads but the cloud app when I open it it again well it reload.

It does not matter if I have two or three things running in the background If I close an app it well reloads and takes longer to load.

Yet there members here who say it stays in RAM.

And yes it even does it to to Apple stock apps so it not just bad written apps.

If I close app than open it well it reloads even Apple stock apps.

Other experiment I open browser playing video than closed the tab and go back to the site and every thing reloaded and took longer to load doing same thing if I closed browser.

So clearly closing the app or tab some thing is releasing it from RAM.

On a PC running windows 7 with 4GB RAM with hard drive well it is faster loading it again it still loads the app and content there is still loading going on.

So clearly some thing is being released from RAM when closing app on like some here who say it not suppose to be released from RAM and stays in RAM.

Well we can only guess what is being put in cache unless you are a hardware engineer but with no proof I can only guess it was the DLL and start up files being cached not the content for faster loading time on very slow hard drives and floppy drives.

Hard drives and floppy drives are very slow and very much so hard drives on laptops if I open app it takes long time to load when I open it again it loads faster but still loads.

Now again we can only guess unless you a hardware engineer but with no proof I can only guess it was the DLL and start up files being cached or part of the app but not the content of app so loading of app again is much faster but there still loading going on.

 

[Danfango]

It’s exactly what I said it was. The app is suspended. The app is moved from suspended to foreground and has to recover state from further down the cache hierarchy (SSD in your iPad)

There are no DLLs on iOS. Shared objects yes and they work very differently (and benefit from cache)