On Tue, Sep 14, 2010 at 5:11 PM, Konstantin Svist <fry.kun@xxxxxxxxx> wrote: > For some reason, while running HDD-intensive tasks (e.g. svn update on > a large tree), system becomes extremely unresponsive. > And I don't mean tasks that require any disk access - I'm trying to type > inside an ssh session in a terminal, and the remote machine is getting > my keystrokes after a pretty long delay. > > Just now, composing this email, thunderbird got stuck at the previous > sentence for a second while it was downloading new messages. > > What's going on?? > I've never thought that there was anything more complicated to this phenomenon than that keyboard and disk i/o are both serviced by interrupts. Not only that, but I think the problem is fundamental. You have two real-time processes competing for processor time and constantly attempting to interrupt one another. Even if you try to set priorities so that keystrokes get first call on the processor's attention, the system has to do a lot of save and restore to respond to each one of those keystrokes, and, unless you don't care about data corruption, some disk tasks, once initiated, absolutely must be attended to. If you push things hard enough, you wind up with a situation that is somewhat analogous to a traffic jam on a freeway: the throughput of the entire system drops precipitously because all of the margins for error have been exhausted, and you wind up with mutually-interrupting processes queued up and traffic nearly at a stand-still. A "fix" could never be more than moving the deck chairs around on the Titanic. Any freeway, no matter how big, can be overloaded, and there will always be traffic jams. Robert. -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
