Exactly. The best possible scenario is that you'd be keeping an app in
memory that, in the current scheme, would have stayed in memory
anyway. Most of the time, though, you'd be hogging memory that could
have been used by apps you were using more often
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Oliver Grawert wrote on 06/08/15 16:35:
Am Donnerstag, den 06.08.2015, 14:33 +0100 schrieb Matthew Paul
Thomas:
Many people do not understand this. Even worse, they think the
opposite -- that closing apps will make their phone faster
somehow. This is understandable if they're used to PCs, which do
work the way they imagine: background apps can consume
processing time, and by sitting in RAM they may cause a
foreground app to use slow swap space instead. But neither is the
case in Ubuntu Touch. Background apps are put to sleep, so they
don't take up processing time.[1] And swap space is small, and
may not even exist at all in the long run,[2] because if memory
is really needed the OS can just close background apps
automatically.
we use zram across the board for swapping currently, not actual
swap space ... so you wont actually notice slowdowns when
something swaps
That's good. But I was referring to PCs in general, as things that many
phone users are used to -- not just to PCs running Ubuntu, in versions
that don't even include the latest LTS. (Or OS X 10.9 and later.)
while all of the above is correct it sadly doesn't really match
reality ... on a 1G device like krillin the app lifecycle
management (or rather the in-kernel lowmemorykiller that we use)
usually don't let you have more than 2-3 apps active in ram and
you end up with OOM killed apps a lot ...
It doesn't matter how many apps fit in memory. Regardless of the
number, it is more efficient for Ubuntu Touch to purge apps from
memory when and only when it's necessary, than for a user to try and
guess when it's necessary. And that's not even counting the time the
person wastes doing it.
if an app gets OOM killed it will be completely flushed from RAM,
there is only a screenshot in unity8 representing it ... once you
flip this app back into foreground in the UI it will be loaded from
disk, this isn't much different from swapping to disk or any other
disk I/O operation, so all you do is to move the slowness into
another place.
if you now take away the ram for one unkillable app on a 1G device
your possible app count goes down from 3 to 2 before you cause any
slowness by re-loading the apps, so on these devices it matters a
lot if you keep an unkillable app running or not just to
compensate for its slow startup time.
...
Exactly. The best possible scenario is that you'd be keeping an app in
memory that, in the current scheme, would have stayed in memory
anyway. Most of the time, though, you'd be hogging memory that could
have been used by apps you were using more often.
- --
mpt
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