Android Memory Management - How does it work?
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- Опубліковано 21 жов 2024
- Smartphones have a fixed amount of memory (RAM). This means that the Linux kernel at the heart of Android needs to manage this finite resource carefully. But what happens when there isn't enough RAM for all the apps you are running?
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You're amazing Gary. No one else is sharing such deliciously geeky stuff. Thank You
That's true. He explains everything real nice 👍
"Refreshing my memory about how RAM works". I see what you did there
😀
Well explained, great video! I started leaving apps open and use most of my ram and let Android do the work for me. And i have a smother experience
That feeling... when you know just too much about a complicated subject, to explaine it in just one video.
Amazing work as always
It is worth mentioning that different versions of android have different ram requirements. Kitkat for example could run on as little as 512mb but ran really well on 1-2gb. It was also 32bit only so it was rare to see older devices with 3gb or more ram. Lollipop and marshmallow could also run well on lower amounts of ram. Lollipop began the transition to 64bit and moving from dalvik to ART runtime. It was really with nougat and up that I've noticed the ram requirements becoming higher, presumably prompting Google to make the Android oreo Go edition, but we now also have more phones utilising faster storage and LPDDR4 or LPDDR4X ram.
@Z3U5 yes I remember my LG G Pad running kitkat had the option to switch to ART runtime under Developer options.
showing some love from Malaysia 😍
Greeting from KL!
Johore !
@@KevinChar me 2
I once used an octa-core Android phone with 1GB RAM. After that, I moved to a quad-core Windows Phone device (specifically, the Nokia Lumia 830) with 1GB RAM. The difference is like day and night, absolutely HUGE difference!
The Android would lag like hell despite multiple cleaning and task kills, while the Windows keeps on performing flawlessly despite every single app run on background (which I can definitely turn them off no problem at all). It just beggars belief!
Professor Sims - Dang, always finish one of your videos being better informed and more appreciative of your talent and work.
Waoh, this is awesome,. Just discovered your UA-cam channel today and would watch all the videos back to back 👏👏 good Job Gary
You explain plain and simple! Very good Gary!
Wish I watched this just when the follow up video is released! The anticipation is killing me! Tell AA to release it soon. As always, love your work Gary!
Thanks for the information , I didn't know about zram. Thanks a lot
Fantastic video that also involves regular Linux behavior.
Enjoyed to listen to your words too.
Now here I am posting this from my Galaxy S5 which is still my daily driver that has just 2GB of RAM available to it.
8:48 that actually explains why chrome randomly reloads all pages... because it was so long in my background that it got it's memory purged
Exactly.
Always liked your explanation. Thanks for making such videos.
It’s been a while since I did Android development, but some things I do remember:
* Quitting an app is quite separate from the termination of the app process. Android may keep the process around after quitting to allow quick restarting of the app. Conversely, as you mentioned, the process may be killed while in the background even if the user hasn’t quit the app, in which case the state needs to be saved for (nearly) transparent restoration when it comes back to the front.
* Java code has a fixed-size, non-reconfigurable heap of something like 30-50MB (this varied depending on the device). Yes, that does seem pathetically small. Native code, on the other hand, is able to allocate as much RAM as it likes. I wrote a test app some years ago github.com/ldo/memory_hog_android that you can use to grab any specified amount of RAM, and watch the effect on your system. In my tests at the time, my devices responded remarkably well...
I should also add that the Linux kernel, by default, uses an “overcommit” strategy for dealing with memory requests. That means in this mode it won’t say “no, I’ve run out”. It can actually cheat because it is very cheap to allocate entries for pages that don’t exist; it doesn’t need to use real memory for them until the process tries to write something to that area. (This is why my memory hog app, mentioned above, has to go through actually writing data into all the memory it has allocated.)
At that point, on a regular Linux system, if it really starts running out of RAM, then this will wake up the dreaded “OOM Killer”, which is a routine within the kernel which will start killing processes in order to free up RAM. On Android I suspect things never get to this point.
Nice one Gary! You are making the complex plain; thanks!
Please compare it to iOS, too!
Yes!
He has another video on iOS. Look for it.
True. He says in that video that iOS for some mysterious reason manages to compress background apps into fractions of their foreground RAM usage. He said he was impressed. Must say I'm impressed too.
@@alliejr that video is relatively old (though still great), a new video only focused on ios would be awesome
medium.com/computed-comparisons/garbage-collection-vs-automatic-reference-counting-a420bd4c7c81
I found this,
Wowww... That was a lot of information sir... Kudos to Gary 🔥👍👍
Truth!
Very interesting video, Gary. I so wish I could convince people who I see swiping apps out of their recent apps list - because they think it's speeding up their phone - not to do it. I tell them that I watch videos like this, and read various articles in my spare time, to learn how it all works, so that they don't have to.
This is such an interesting process and I regret not trying to know this earlier.
Thank you Sir Gary, this is enlightening.
5:03 Swap Memory Explained
In short it's kinda like virtual memory is, in Windows. Instead android has zram/compressed ram(instead of storage), where things are sent after compressing.
For more details hear gary explain it.
Finally, someone explaining a complicated problem in layman's terms. Better than my lecturer.
Always wondered about all this worked in comparison to my PC ...well explained
As a CS student... cool video!! Thx
Found it be really interesting and unique, very nicely explained, Thanks
Nicely explained as always. I would like to see videos on custom ROMs, basic electronics for computers, encryption and computer graphics. Have a good day.
Thx. I did two videos on encryption already: ua-cam.com/video/clWEKq8CVOk/v-deo.html and ua-cam.com/video/rLiEA06Bcic/v-deo.html
Wow! Amazing! Absolutely superb explanation.
After watching dis vid, my available RAM went down to 600MB ._.
lol
your memory is that much low that you had to write 'dis' and 'vid'...
@@ikgeek yea tru lol
Funniest thing I've ever seen on Android was a glitch ig, that showed I had negative amounts of ram free. I don't know if I still have the screenshot to upload but I'll look for it.
Found it:
Negative Ram? imgur.com/gallery/XbPGiVg
Excellent Video. Really love the content.
I love you Garry. Because of these informative videos.
Snapdragon 710 vs 835 speedtest g
It's obvious... 835 is still a beast.
@@projectz9776 I know but it would not be a actual comparison but rather this test would show that how close sd710 comes 2 sd835
@@CosmicThinker01 but i want Snapdragon 675 vs 835 becoz 675 based on A76 & leaked Geekbench single & multicore score is 2200 & 6000 respectively
The GPU in the 835 is on a different league if compared to the 710, which in turn will breeze through the GPU part of the test.
@@yashchoudhari278 yup but there is no sd675 phone in the market right now
Really good explanation! Regarding the ZRAM, can you do an update video about Oneplus's RAM Boost feature? I'm confused as to how it works and if it's any useful. With RAM Boost enabled the swap size is 2GB, that seems like a lot of CPU wasted to constantly compress/decompress.
thanks so much sir. I have a semenar about ram management in android. You save my life
.....
This is why I love your videos, you explain better and faster than my Teacher in the university xD.
Neat. Looking forward to the next video on ram.
How does it not work?
Just kidding Gary, love your videos, each one is so well made and explanatory, thank for your work!
0:12 is your memory dynamic
"Gary Explains" at its finest.
Thanks For this explanation looking forward to the video in AA.
Please make one on iOS side of things as well, you mentioned it on AA in an old video. Would love a detailed version
Would be nice to have a video on why newer Android OS uses more ram than previous ones. And why some Android phones are harder to root than others.
*GARY!!!*
*Good Morning Professor!*
*Good Morning Fellow Classmates!*
MARK!!!
Mark!
Good day!
MARK!
MARK!!!
ZAMAN!!!
SACCHI!!!
The omnipresent MARK!!!
This is the first time I'm hearing of ZRAM. I had always assumed Android uses a page file like Windows. Thanks Gary!
Why does this work better than saving to virtual memory / a paging file though?
maybe becouse it was faster than writing page to disk, cmiiw
Paging to solid-state storage doesn’t work very well. Repeated writes will wear out the storage.
It will wear out the flash storage because of the repeated write/read cycles.
Looking good Gary
I’ve run performance tests between iOS and Android Linux and found the page size (the 2 are different) makes a performance difference. So, writing an app that performs well on iOS will perform differently for the same structured app on Android (understand that neither share the same language) because of the memory management. Also are you making the distinction between paging (within the app) and swapping (rolling out the whole app to use it’s memory)? Both of these terms were first known to exist from mainframe VMS days in the early 1970s and were long in the coming to smaller servers. Thanks for this lecture. I enjoy it very much.
Sir great video with easy to understand information of the topic.
Can you make a similar video of how iOS manages ram and how is is capable of keeping more apps in ram without reloading when the actual amount of ram is pretty less for ex 2GB (when compared to android devices)?
Did you see this video of mine? ua-cam.com/video/lCFpgknkqRE/v-deo.html
Amazing work!!!
Thank you so much 😀
Thank you so much.
Uncle Gary is a guru. Uncle Gary could produce a smartphone.
Thanks from Egypt
Gary, is there a way that you could make a video about Kernel adiutor? I would like to tweak my (custom) kernel to my likings and make different profiles for different occasions but there are so many options there, and I don't know what some of those things are.
Great video!
How much ram does gary have in his mind? He has loaded so much in his mind, and everything is seamlessly delivered instantly!!! ..
0:12 I see what u did there, great video as well
Great info 👍🏻
Hey Gary! You need to do more iOS tech topics as well.
as they say:
BRILLIANT !
Thanks Mr Gary! Very informative!
For example, OEM xiaomi Miui very aggressive in their MM - How much can the OEM change the Android MM?
Well explained
does a 3rd party launcher affect the Ram management ??? facing issues on my Pocophone while using Nova prime.
Thank you sir👍
Impressive. If you make an app to teach some definitions like that, I would be the first one to buy it
Informative
Thank u garry
My 2016 Android tablet has as much RAM as the laptop I'm typing this on - 2GB - running Linux Mint. Thing is, I cannot run more than a single app on Android without the POS operating system killing a second one. Linux, using the same 2GB, and swap, will NEVER kill running apps indiscriminately. It will as you've said, cause 'disk-trashing' but that is infinitely preferrable to killing, without warning, running programs. Also, Android apps do a piss-poor job when it comes to restoring the state of a killed app.
So, continuously comparing Linux to Android throughout the video raises my blood pressure. Linux has been doing PROPER multitasking since forever, while what Android does is not proper multitasking. You could argue that even Windows 3.1 does a better job of multitasking than Android does - it at least suspends apps to the background, rather than killing them like Android does.
And while Android does use the Linux kernel, it's first butchered by Google. I've read that Google intentionally chose the 'killing-apps' route as it increases the ad-revenue generated as all restarted apps will also have to reload the Google ads. And I believe it! Most Linux developers also cringe at the Linux/Android comparison. There is a reason that Android has not been adapted for desktop environments - no one would accept the abysmal performance it offers.
What's really sad is that billions of users accept Android's shoddy performance as normal. After using my Android tablet for a few weeks, and watching in disbelief how it would without warning kill background apps, I chucked it and swore I'd never again buy an Android device. Come to think of it, an old Windows CE device of mine performs better than Android does. Come back M$, all is forgiven.
Gary. I want you to de clearify people about XR battery that why it has shortest battery life when test with other flagship phone because it use LCD which consume more energy than OLED when we use in high brightness.Pls make video about this.
Refreshing my memory... Haha I see what you did there
Gary is the REAL professional not FAKE like Rere Ritchie
6GB feels like pretty okay!
All this time whenever i played pubg or honkai impact 3 at maxout graphic my devices always had well over 1gb ram to spare!
Thank you professor...can't wait for part two on the Android Authority channel 👍🙏
Does GPU has it's own Video memory or it uses ram as video memory in a smartphone ?
Android doesn't have any RAM or VRAM memory. Android is, like windows and iOS, just an OS.
Edit: It's a pretty low move to edit your comment without mentioning it so the reply doesn't make sense.
@@wintermelon4020
you actually not answering anything of what he asked about ! he doesn't even mention "Android" in the Question!
So im guessing here right now, but I've never heard anything in that direction so I would come to the conclusion, that the GPU in a smartphone does use the normal RAM.
@@PrinceMody97
Isn't it obvious? He edited his comment...
@@wintermelon4020
Oh I'm sorry, It was obvious but I didn't think he edited it 😬
So does desktop linux distro like arch linux use zram?
9:23 when gary realizes he screwed up in his recent app project
Do you think think we should use third party ram manager?
Is it still posible that an app can use exploits to enter in system partion? I mean in the latest android versions. The develpor has to made the virus app foar a certain ROM's vulnerability or it works for all ROMs? Im asking this because i use a lot of mod apps and games. 🤣
By experience, i found out that 4gb of ram as of 2019 is really enough.
The only thing that would prove this wrong, is that if for whatever reason you want open more than 1 really heavy game.
But realistically speaking, ppl dont do that, so 4gb is fine, or you can just go 6 for peace of mind. Pocof1 for example.
Basically now if you're buying a new phone and you're at least a moderate user, you SHOULD have 6GBs of RAM. You don't HAVE to, however 4GBs is just not cutting it properly. I just moved from the S7 to Note 9.
What if in case if we use running services like ok Google detection or call recorders etc? What will happen?
Does the same principle applies also to iOS or windows?
It would be great to (know and) compare this to the RAM management of iOS. How comes that it seems to need much less RAM and offer a fairly good retrieval of the processes?
android is really stupid on managin the resources. ios i do not know but it seems to be well engineerd, android it theory works but here in realworld its just shit.
I've been facing a very annoying issue. For example: when I'm playing a game and listening to Spotify, and then I pause the music... It's enough for Android to completely kill the Spotify process. Then I have to open Spotify again to continue listening. And frequently, when I go back to the game, guess: it's not where I left it anymore, it's starting from scratch. Android 10 galaxy s9 4GB RAM. Appreciate any comments...
I feel like I need a minimum of 8GB of ram on my smartphone. I have the OnePlus6t and I feel like it is the right amount. Why? This device doesn't slow down or stutter and I had it since it launched. So, in my opinion, 8GB is the right amount. Can't wait for the next video to see if i am right 😂
So is zram good or should i get a phone that doenst have it? Like a oneplus 6t
Linux kills apps when it runs out of virtual memory and needs to allocate more. You can run it with zram or zswap but without a swap file or partition and it will work the same as on an Android phone. I miss compcache though. That allowed xz compression that I don't have access to anymore. It didn't matter that it was slower per operation. The compression ratio is so much better than gzip that it was still faster because it made more room and didn't need to be called as often and gzip still left the need to use swap on the SSD or HDD. Just left swappiness at default so the least likely pages to be used in the near future would be compressed with less notice.
my phone has 8 GB ram but only 4.79 GB is available, if I need more than 4.79 GB to run two big games like shadow gun legends and call of duty will my phone be able to borrow more ram from the system to meet the 6 GB requirement to prevent one of the games from crashing in the background is this what your saying it's all so very confusing thanks gary
I need my game to run in the background, while I do other stuff on the phone without the game shutting down or going to sleep. I use OnePlus 7Pro. Thanks
That doesn't make sense. The compression will take some overhead and use up precious RAM that we've run out of. Why not just write to internal memory instead?
Swapping to flash will kill the flash very quickly. Flash memory only has a fixed lifetime of reads and writes.
Please can you do the same video for iOS?
I heard that apple has better ram management than android
is it true
what does they to get better ram management
What smartphone daily driver?
I have 8GB on my Windows PC and I sometimes open dozens of apps in the background, and they all seem to be still stored in RAM and never have to be loaded again into memory, and I still have over 1GB of available memory even when all these apps are running in the background. On the other hand, my 4GB Android phone needs to reload apps after I load 5 or 6 light apps onto memory, and it always seem to have mere megabytes left of available RAM. What gives?
@Sumeet tanwar I actually have an SSD, so I'm not sure how much virtual memory is allocated for SSD, because each write shortens the lifespan of the SSD. Maybe there's some other wizardry involved.
Interesting is why manufacturers still have an aggressive ram management although their flagships have 6 or even 8GB of ram. Or another interesting question: why do they find the urge to tweak Android to do it their own way.
Those are all good questions. One possible answer about the aggressive RAM management is that it is actually sometimes a battery saver that kills the apps rather than a RAM saver.
can u please explain how ram managment is taking place in ios, which makes ios ram managment better than android's
watching on maclaren edition op6t
Mclaren*
If i record a video, record a camera, or play a game, and come back from another app, the app is refreshed, is there any solution?
Well i still experimenting my Nexus 6's 3gb ram.. with or without zram... differences is app opening while on background (multitasking). Android wasn't completely learned about ram management for me... That's why it needs more RAM... I think 🤔🤔🤔
Not sure about the bad idea thing. Often times if my phone memory is full my phone starts to slow down until I clear some memory. Maybe my phone processor ucks and assume that if CPU is not bottlenecking maybe full memory is a good idea.
I hope that the developers are really2 do some best ram management rather than relies on massive ram. It should be enough for mid range phone using 4gb ram. Just OPTIMISE. Really hate when some apps sti have ram leak. IDK whether the developer lazy or they really dont want to optimise due to the nature of andriod that usually have massive ram resources.