On Nov 6, 2012, at 8:08 AM, Alex Zavatone <z...@mac.com> wrote: > > On Nov 6, 2012, at 9:23 AM, Jean-Daniel Dupas wrote: > >> >> Le 6 nov. 2012 à 12:13, Tom Davie <tom.da...@gmail.com> a écrit : >> >>> >>> On 6 Nov 2012, at 11:01, Nick Rogers <roger...@mac.com> wrote: >>> >>>> Hi, >>>> >>>> Thanks for the replies. >>>> I was trying to achieve what essentially "free memory" apps on the Mac >>>> AppStore do. >>>> The RAM usage can be divided into four parts as shown in Activity Monitor. >>>> 1. Free >>>> 2. In-active >>>> 3. Active >>>> 4. Wired >>>> >>>> When I used my earlier app to allocate memory equal to free + inactive >>>> bytes, for the execution of the program it used to make the system less >>>> responsive for a few seconds and on release and quitting the app, most of >>>> the inactive memory would shift under free. >>>> >>>> e.g. if free is 1GB and inactive is 1.5GB, then after run, free would be >>>> 2.45GB and inactive just 50MB. >>> >>> Why on earth would you want to release inactive memory? This is memory >>> that is in use by applications, just ones that haven't been scheduled in >>> for a while. This RAM IIRC is automatically paged out to disk, so that if >>> it is needed it can simply be overwritten, just like free memory, but has >>> the side benefit that if it's not overwritten, then the inactive >>> applications can be brought back to life very fast. >> >> The memory is paged out to disk only if it is read-write memory that was >> modified, and is not already on the disk. All mapped frameworks, the full >> content of the "Unified Buffer Cache" (which generally represent most of the >> inactive memory) and other stuff are keep in RAM to provide faster access, >> but are already present on disk and will be simply discarded if the system >> need more RAM. >> >> So not only freeing inactive memory is useless, but it is also guarantee to >> make your system slower. > > Actually, that's not always the case. As I use Safari through out the day, > Safari ends up eating 6 to 12 GB of data on my 16 GB system. Frequently, I > need to issue a purge to get back a spare GB or few hundred MB. Plus, if > you're booting off, or have your swap file on an SSD disk related performance > penalties will be much less than if using an HD to hold the swap file.
Memory remains the target of much superstition. The OS will take care of managing memory--you don't need to do it. Common utilities like Activity Monitor and Task Manager have given micro-managing users an excuse to second-guess their OS, which is rarely wise. Preston _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
