Basic OS meanining, explorer or windows, the keyboard for android and just app switching and high level OS features. Ever since I started using a computer, other than DOS & *nix, I always questioned why essential applications slow down.<p>When these applications slows down, it really hinders the user experience and forces users to upgrade(maybe this is why). Ever since I was a kid, I was always hopeful that the next release a new OS would solve this problem. This never happened.<p>When smartphones took off, with Android and IOS, I was again hopeful that, this time the issue would be addressed. In a sense, I was happy with IOS and OSX, the high level OS application layered for the most part, has higher level isolation. It is rare, that third party applications effect and slow them down. However, it still slows down.<p>Is this a real hard problem to solve? I would sacrafice, dedicated 20% of CPU/Memory, locked into these apps, so I never see slow down, when switching windows. Or is this not even an option to do? If so, why is it that the OS cannot reserve CPU cycles for itself that can never be touched by third party so it is always fast.
> Is this a real hard problem to solve?<p>Somewhat. On the one hand, you have plain old feature creep – people expect smoother animations, more animations, more features, better fleshed out features, … and it's hard to resist those demands when you want to sell your software.<p>One the other hand, you have security and reliability. All those error checks, bounds checks, canary checks, validations, secure hand shakes, … take up time, and it accumulates. DOS was fast, but it was also terribly insecure and most programs crashed regularly.
Reserving CPU for itself will make all third party app run slower. And third party apps are a huge selling point (look at Windows Phone), you don't want to be behind your competition because you want a smoother experience on your stock applications.<p>Also there is feature creep, the longer the system goes on the more feature, security checks, fixed, etc... your basic system does and that will exponentially increase the weigth of your system, requiring you to serve more and more, and making everything else slower.
There's nothing "basic" about the core file manager/windowing system/explorer. It is one of the more complex processes, and will invariably grow since the potential feature set is near endless.<p>An on screen keyboard doesn't have to be complicated, but once you add swype/multilanguage/dictionary/speech input/etc then it starts to require more IO to initialize.<p>iOS was lag free pre-apps. Then people wanted apps, then legit multi-tasking, and then tons of services from the OS to support multi-tasking apps. Now you'll be running a dozen or more full time processes even excluding the kernel.<p>> Is this a real hard problem to solve?<p>It is an easy problem to solve. You'd just have to give up tons of features and functionality.<p>> I would sacrafice, dedicated 20% of CPU/Memory, locked into these apps, so I never see slow down, when switching windows.<p>That wouldn't help. Many things are IO bound not CPU/memory bound. Plus on mobile there is still the battery X factor.<p>> Or is this not even an option to do? If so, why is it that the OS cannot reserve CPU cycles for itself that can never be touched by third party so it is always fast.<p>Sure it can. Almost all operating systems allow you to set a process as high priority for scheduling. It just doesn't do much, because as I said it is IO bound not CPU bound, and plus sometimes processes are waiting for an atomic lock to come free and by prioritizing the process in the spin, you've actually slowed and delayed the process who needs to finish up and free the lock actually adding lag (this was a BIG problem on Windows in particular, which is why they actually split several kernel level atomic locks).
some answers from Android Performance Patterns: <a href="https://www.youtube.com/watch?v=T52v50r-JfE&list=PLWz5rJ2EKKc9CBxr3BVjPTPoDPLdPIFCE&index=22" rel="nofollow">https://www.youtube.com/watch?v=T52v50r-JfE&list=PLWz5rJ2EKK...</a>