On Sat, Jun 14, 2008 at 10:55:52PM -0400, David Higgs wrote:

quoted text
> On Sat, Jun 14, 2008 at 9:16 PM, Henning Brauer  wrote:

> > * David Higgs  [2008-06-15 01:59]:

> >> On Sat, Jun 14, 2008 at 1:11 PM, Henning Brauer  wrote:

> >> > * Toni Mueller  [2008-06-14 11:29]:

> >> >> Would it be possible to walk along the live table, without copying the

> >> >> table, or would the continuous stream of route inserts and deletes lead

> >> >> to a corrupted view and/or access to the wrong parts of the system's

> >> >> memory (which must to be prevented), or would this be such a

> >> >> performance hit that this is unfeasible?

> >> >

> >> > userland can walk a kernel table since when exactly?

> >> > (leave dirty /dev/mem style hacks aside)

> >>

> >> If the kernel table is kept in an ordered state, userland could

> >> provide a "starting value" or key.  The kernel can then return the

> >> requested chunk (up to the size requested) starting at the "next"

> >> table item that comes after the key.

> >

> > wow. you completely miss the point.

> > userland cannot poke in kernel memory.

> > (footnote: ok, it can, but assuming it can't is better)

>

> I knew that, but I explained myself poorly.  I was thinking something

> along the lines of making a different route sysctl (other than

> NET_RT_DUMP) that can copy out smaller portions of the routing table

> at a time.  Userland programs could then iterate their way through the

> routing table.

>

> Depending on the structures being copied out, this might be completely

> unworkable.  On top of that, you'd at best just push back the limits

> on available real memory.  Best to wait for a restartable route

> sysctl.

>

> Apologies for the noise and my out-loud musings.

> 

Yes that's more or less what needs to be done. I'm willing to look at

diffs and help working out the evil guts of this.
--

:wq Claudio