On Tue, Jan 16, 2001 at 09:03:45PM +0100, Andi Kleen wrote:
> On Tue, Jan 16, 2001 at 06:38:28PM +0100, Gleb Natapov wrote:
> > Hello,
> >
> > Recently I noticed that when I simultaneously do 'up' to many network
> > interfaces
> > (many is ~15) netlink drops part of the messages about interface state
> > change and thus
> > my userspace tools don't know that some interfaces are in up state now. The
> > error that
> > I get from netlink socket is "No buffer space available".
> >
> > After looking at the code I saw that the only way I can get such error from
> > netlink
> > is if sk->rmem_allock is bigger than sk->rcvbuf. I can enlarge sk->rcvbuf,
> > but for each
> > interface I receive six messages and each of this messages is smaller then
> > 200 bytes.
> > the default size of sk->rcvbuf is 65535 bytes, so why messages about 15
> > interfaces can't
> > fit in default buffer size?
>
> Because the sk_buff header size is accounted too.
> sk_buffs are not lightweight.
>
Here is how NLMSG_GOODSIZE is defined:
#define NLMSG_GOODSIZE (PAGE_SIZE - ((sizeof(struct sk_buff)+0xF)&~0xF))
So sk_buff header is not an issue here.
--
Gleb.
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