site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com On May 30, 2007, at 7:47 AM, James Bucanek wrote: = Mike _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... I'm hoping this is the correct list. It sounds like a Kernel issue. Feel free to enlighten me if it's not. I'm looking for a way to reload pages that have been paged out by another process. They scenario is pretty simple: I've written an application that uses a lot (100s of MB) of RAM. Users run the application (it's a backup utility). Applications does its thing and terminates. Users now complain that their system is "sluggish and unresponsive." The problem, obviously, is that as the application ran it forced just about everything else in RAM to be paged out to the VM backing files. The OS then spends the next 30 seconds, or more, paging it back in -- a period of time my users describe as "eternity." Is there anyway for my application to send a "hint" or command to the VM manager that will cause it to reload the recently paged out memory pages? I have a supervisory process (a scheduler daemon) that can do this after the process terminates. No, there isn't. The system has no way of telling the difference between pages that were evicted but still relevant and pages that were evicted and not relevant; it has to wait for other applications to need them. Brian's somewhat terse observation might bear a little expansion, though I think he may be on the right path. You say your application is a backup utility, and that it uses hundreds of megabytes of RAM. What do you mean by "uses"? Do you make large allocations inside your application's address space? Why? If you are buffering for a device, you can probably get by with much less buffer than you think; certainly not hundreds of megabytes. As a backup utility, you are probably reading a lot of files; as Brian notes if you apply the F_NOCACHE fcntl to these files immediately after opening them, you will avoid evicting other applications' pages in favour of file cache pages. You should only do this for files you are only reading once; if you read a file more than once in a relatively short period of time, or you write it with the intention of it being read shortly thereafter you're better of letting the system cache it. HTH; feel free to ask more questions. Your users, incidentally, should buy more RAM. 8) This email sent to site_archiver@lists.apple.com