Messages in this thread | | | Date | Sat, 30 Aug 2003 20:30:36 -0300 (BRT) | From | Marcelo Tosatti <> | Subject | Re: Andrea VM changes |
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On Sun, 31 Aug 2003, Andrea Arcangeli wrote:
> On Sat, Aug 30, 2003 at 04:21:02PM -0300, Marcelo Tosatti wrote: > > y > > > > On Sat, 30 Aug 2003, Marcelo Tosatti wrote: > > > > > > > > > > Indeed, you are right. > > > > > > > > I'll start looking at them Monday. I'll keep you in touch. Thanks. > > > > > > Andrea, > > > > > > Would you mind to explain me 05_vm_06_swap_out-3 ? > > > > > > I see you change shrink_cache, try_to_free_pages_zone, etc. > > > > > > Can you please give me a detailed explanation of the changes there? > > > > > > I appreciate very much. > > > > > > I'll keep looking at other patches for now. > > > > 05_vm_09_misc_junk-3 removes the PF_MEMDIE and you also seem to remove the > > OOM killer. Is that right? Why? > > because the oom killer is a DoS on servers, on a database setup, with 2G > free, with say all tasks 2.7G large, it'll start killing all the > thousand database tasks instead of the 2g netscape task that hit an > userspace bug and it started allocating ram in a loop, and that will > make no progress since no physical ram will be released. There's no need > of oom killer to keep the system stable, with my vm, and the current > probabilistic oom killer in the page fault hander
So tasks get killed in case of page allocation failure?
> kills the right task most of the time (unlike the stock oom killers that > works well only for the desktops or developer machines). So it does a > much better job and it doesn't risk to DoS the box due oom.
Mind to explain me in more detail the OOM killing mechanism?
> Another DoS generated by the oom killer is that it'll try forever to > kill a UNINTERRUPTIBLE task hanging in a nfs server that is down, so it > hangs the whole box for an unlimited time. > > I've an algorithm that will work, and that will provide very good > guarantees to kill the "best" task to make the machine usable again, > with the needed protection against the security DoSes, but it's in > no-way similar to the current oom killer.
My concern is about how this oom killer works.
PS: Thanks for answering, hope we can agree on things and make progress on this merge.
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