Re: [patch 016/104] epoll: introduce resource usage limits

Davide Libenzi
2009-01-28T04:10:54Z

On Wed, 28 Jan 2009, Bron Gondwana wrote:

> On Tue, Jan 27, 2009 at 07:46:18PM -0800, Davide Libenzi wrote:
> > On Wed, 28 Jan 2009, Bron Gondwana wrote:
> >
> > > On Tue, Jan 27, 2009 at 04:35:19PM -0800, Greg KH wrote:
> > > > Can you resubmit all 4 patches, and cc: the epoll author, Davide? He's
> > > > the one that needs to accept these changes.
> > >
> > > It's three now (two of them deserved to merged) and re-ordered so the
> > > first two are trivial and the complex bits are easily skipped if you
> > > don't want them.
> > >
> > > Just looking for Davide's email address. Found it :) I'll follow up
> > > this message with the patches. I'm not going to CC everyone else again
> > > - but I'll CC LKML so you can follow it there if you want.
> >
> > I already gave you my opinion on such code. There is no need for it. If
> > your servers are loaded, in the same way you bump NFILES (and likely
> > even other default configs), you bump up max_user_instances:
>
> How can you tell if it's heavily loaded if you can't tell what the
> current usage is? Just wait until you hit the limit?

In my servers, I know if they are going to be loaded, and I bump NFILES
(and a few other things) to the correct place. Since many of those
limits do not actually pre-allocate any resource, I don't need to wait and
monitor the values, before taking proper action.
Sorry, the whole patch set is a big NACK for many reasons.
We'd have happily avoided those limits altogether, but 100-160MB of kernel
memory able to be pinned by unprivileged users is easily a DoS on multiuser
systems.

- Davide