Virtual memory size (OSX.4.6) ?
in [Mac Systems]
|
From: Claude-Albert Berseth on 8 Apr 2006 13:27 Hi all, I have a problem understanding how virtual memory is counted : - The activity monitor shows 4.36GB of Virtual memory - /private/var/vm/swapfile* files have a total size of 512MB I verified that these are really the active swapfiles. There are 59 processes, a dozen of which are displayed as "active". So what does the Virtual Memory mean ? Is it the maximum size that an application could claim ? Or is this VM heavily compressed ? As for RAM, the match is good, my 512MB are almost fully used... Powerbook G4/667, OSX.4.6, 512MB RAM Thanks in advance for your ideas... Claude-Albert
From: Jon on 8 Apr 2006 13:35 Claude-Albert Berseth <void(a)nospam.com> wrote: > As for RAM, the match is good, my 512MB are almost fully used... > Powerbook G4/667, OSX.4.6, 512MB RAM Before all the others start explaining things: Get more RAM! IMHO, no Mac should hve less than 768, preferably 1GB or more. It will do wonders to performance and response. VM is slo-o-o-ow in comparison with real RAM, no matter what you do, and the less the Mac needs to utilize it (i.e., swap in and out) the better. -- /Jon For mail address, run the following in Terminal: echo 36199371860304980107073482417748002696458P|dc Skype: storhaugen
From: Claude-Albert Berseth on 8 Apr 2006 14:25 Jon wrote: > Claude-Albert Berseth <void(a)nospam.com> wrote: > >> As for RAM, the match is good, my 512MB are almost fully used... >> Powerbook G4/667, OSX.4.6, 512MB RAM > > Before all the others start explaining things: Get more RAM! > IMHO, no Mac should hve less than 768, preferably 1GB or more. It will > do wonders to performance and response. VM is slo-o-o-ow in comparison > with real RAM, no matter what you do, and the less the Mac needs to > utilize it (i.e., swap in and out) the better. Sure enough, Jon. I ordered 1GB a few days ago, I can't wait to see the improvement !!! I think 512MB was ok (sort of) up to X.1 or X.2 but the system has become very heavy since then ...
From: Hans Aberg on 8 Apr 2006 14:39 In article <c7681$4437f288$5448a851$21543(a)news.hispeed.ch>, Claude-Albert Berseth <void(a)nospam.com> wrote: > I have a problem understanding how virtual memory is counted : Just forget about it - it is too complicated. :-) > So what does the Virtual Memory mean ? Is it the maximum size that an > application could claim ? Or is this VM heavily compressed ? Mac OS X has BSD UNIX at the bottom, which divides the RAM into pages, which each, I think is 1 kB. When RAM is getting short, pages that are thought to be less active by the OS are swapped onto the hard disk. Each program has a number of active data sections, each which can hold a virtual memory byte map of the maximum address space, which is 2^31 bytes, which comes from the fact that one uses 32-bit addressing, and reserves one bit for a sign. The UNIX kernel makes each program think it has all that memory available, even though in?practice it is limited to hard disk size. Now, this stuff is not very important to you as a user, because it is hidden away. What is important to you and other users, is to ensure that the active program parts are kept in RAM and not swapped out on the hard disk, because the hard drive is about a hundred times slower than the RAM. So if you have too little RAM, your?computer will slow?down?enormously, as it will spend all its time waiting for hard drive accesses to finish. If you go into the utility Activity Monitor/System Memory, the Page Outs field at the bottom, and get a lot of those when you are swapping programs, then you have too little RAM. The same if trying to conduct an operation within a program. The RAM is then too short, as it means that normal user operations will cause active program parts (pages) to become swapped out on the hard disk: only those that are relatively inactive should be swapped out, for the OS to be able to work efficiently. So then you need to get hold of more RAM, or alternatively, have a lot of patience while working with your computer. :-) -- Hans Aberg
From: Adrian on 8 Apr 2006 16:12
Claude-Albert Berseth <void(a)nospam.com> wrote: > Sure enough, Jon. I ordered 1GB a few days ago, I can't wait to see > the improvement !!! > I think 512MB was ok (sort of) up to X.1 or X.2 but the system has > become very heavy since then ... Be sure to post your findings. I have always had an unnatural desire for lots of RAM myself (!) but I am also aware of situations where the much vaunted speed benefits haven't been particularly evident to some people after an increase (depending on their applications usage, of course). -- Adrian |