On Fri, Jun 13, 2008 at 04:20:45PM -0700, Philip Guenther wrote:

quoted text
> On Thu, Jun 12, 2008 at 3:47 PM, Toni Mueller  wrote:

> > as of today (I didn't notice it earlier), I see this problem on one of

> > my machines:

> >

> > # netstat -rnf inet

> > netstat: sysctl of routing table: Cannot allocate memory

>

> "netstat -r" dumps the routing table by calling sysctl() twice, once

> to get the size of the table so that it can allocate enough memory to

> hold it, and then a second call to actually fill it in.  That error

> means the routing table grew between the two calls, so the second call

> could return the entire table.

> 

Nope. That is not the problem. The main issues is that a full view will

need a lot of memory for the sysctl. This memory needs to be available as

real memory because it is wired into the kernel. If you run bgpd with full

views on a box with less then 512MB of RAM you're most probably run out of

memory. Theo and I had a look at this and bailing out in this situation is

the right thing to do. The right fix is to just spend 50 bucks on 1-2GB

of additional RAM.
>

quoted text
> > Any idea about how to combat this, please?

>

> The code will need to be changed to

> a) add a fudge factor to the size that was returned, and

There is already enough fudge in the sysctl itself. The estimate done by

the sysctl in the first run is 10% over the needed memory.
> b) retry the pair of calls if the second returns ENOMEM

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> 

Will not help either.
c) work around (ugly but works)

netstat -rnfinet -M /dev/mem
d) the route sysctl needs to be rewritten to be fully restartable and so

small chunks of the table can be fetched one after the other. This is a

massive change and it will not happen for the upcomming release.
--

:wq Claudio