Re: [take6 1/3] kevent: Core files.

Andrew Morton
2006-08-11T06:24:13Z

On Fri, 11 Aug 2006 10:15:35 +0400
Evgeniy Polyakov <johnpol@2ka.mipt.ru> wrote:

> On Thu, Aug 10, 2006 at 05:56:39PM -0700, Andrew Morton (akpm@osdl.org) wrote:
> > > Per kevent fd.
> > > I have some ideas about better mmap ring implementation, which would
> > > dinamically grow it's buffer when events are added and reuse the same
> > > place for next events, but there are some nitpics unresolved yet.
> > > Let's not see there in next releases (no merge of course), until better
> > > solution is ready. I will change that area when other things are ready.
> >
> > This is not a problem with the mmap interface per-se. If the proposed
> > event code permits each user to pin 160MB of kernel memory then that would
> > be a serious problem.
>
> The main disadvantage is that all memory is allocated on the start even
> if it will not be used later. I think dynamic grow is appropriate
> solution, since user will have that memory used anyway, since kevents
> are allocated, just part of them will be allocated from possibly
> mmaped memory.

But the worst-case remains the same, doesn't it? 160MB of pinned kernel
memory per user?