Messages in this thread | | | Date | Sat, 15 Aug 1998 17:00:38 -0400 (EDT) | From | Matt Agler <> | Subject | Re: A true story of a crash. |
| |
On Sat, 15 Aug 1998, Albert D. Cahalan wrote: > Our current situation is bad. At the very least, Rik van Riel's process > killer will not be worse than what we already have. I expect that most > people will find it much better than merely "not worse" though. > > > It would be better and simpler to let the user or admin decide what to > > kill. Instead of killing a process, we should put it to sleep. > > End result: 100% memory use, 100% idle, all processes stopped.
That depends on implementation. Of course, if you let every last page get used before doing anything, you're stuck.
> > If the machine has overextended itself, we're probably swapping like mad > > already. It's hammered. We're not getting anything done. We don't need > > efficiency anymore. We want recovery without loosing in-process work. > > Not possible.
Gee that was fast.
> > For example, let's put each process, that asks for a page that we can't > > give, to sleep (from do_no_page?). This would be a special sleep in that > > it doesn't wakeup until we return to a certain threshold of free memory. > > What would happen is that it's pages would age and get thrown out. > > Thrown out? You must mean that literally, since there may be no more swap. > The process will be really messed up if you send pages to /dev/null.
No, I was referring to text pages. They don't use swap. Sorry.
> Hostile users can just use a daemon to grab the last bit of memory > that you reserved for root. (finger, telnet, whatever) > > With the overcommit, random events could be enough to eat up all > the reserved space.
Like I said, there is definitely the admin factor here. This is not a countermeasure for any kind of attack. I'm just pointing out another option besides SIGBUS. If a production machine's kernel suddenly kills off your main app because you mistakenly underestimated resources, you may want it to wait until you have a chance to give it more resources instead of just killing it off and making you start over. ext2fs reserves a bit of space for the admin. Perhaps a bit of swap should be reserved also. The admin now has _MORE_ options.
-Matt
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.altern.org/andrebalsa/doc/lkml-faq.html
| |