Re: Restructuring ARP cache

[Ryota Ozaki <ozaki-r%netbsd.org@localhost>]

On Mon, Aug 17, 2015 at 6:23 PM, Ryota Ozaki <ozaki-r%netbsd.org@localhost> wrote:
> Hi,
>
> Here is a new patch that restructures ARP caches, which
> aims for MP-safe network stack:
> http://www.netbsd.org/~ozaki-r/lltable-arpcache.diff
> (https://github.com/ozaki-r/netbsd-src/tree/lltable-arpcache)

Updated the patch. The changes are:
- Fix freeing mbuf in lltable_drain
- Fix rtentry leak

  ozaki-r

>
> The patch replaces old llinfo for ARP caches with
> lltable/llentry derived from FreeBSD.
>
> Highlights of the patch are:
> - Import lltable/llentry from FreeBSD
> - Use llentry instead of llinfo to manage ARP caches
>   - ARP specific data are stored in the hashed list
>     of an interface instead of the global list (llinfo_arp)
> - Fine-grain locking on llentry
> - arptimer (callout) per ARP cache
>   - the global timer callout with the big locks can be
>     removed (though softnet_lock is still required for now)
> - net.inet.arp.prune is removed
>   - it is the interval of the global timer callout
> - net.inet.arp.refresh is removed
>   - it is a parameter that prevents expiration of active caches
>   - Removed to simplify the timer logic, but we may be able to
>     restore the feature if really needed
>
> One aim of the changes is to proceed the nexthop cache
> separation that was raised in the thread "Improving use
> of rt_refcnt", although the routing table is not changed
> by this patch. I'll proceed it if we have consensus on
> the approach.
>
> Any comments and suggestions are appreciated.
>
> Note that the patch of course passed the ATF tests :)
>
> Thanks,
>   ozaki-r