[Cerowrt-devel] cerowrt-3.6.9-3 test release

Robert Bradley robert.bradley1 at gmail.com
Sat Dec 8 12:53:55 EST 2012

On 07/12/12 08:20, Dave Taht wrote:
> Also, some new unaligned exception traps have surfaced with ipv6. They
> are not bad - only about 1200 on a 60 second rrul test with 24.5/5.5
> ceroshaper, but enough to dramatically affect ipv6 latencies, and
> affect fq_codel. (see attached)

I have managed to track down possible causes of these new traps now.  
I've noticed that in the IPv6 stack in particular, there's a tendency to 
access the flow label and traffic class fields by casting the header 
structure to __be32*.  Needless to say, this ends up producing a lot of 
unaligned access traps.

There's a possible issue with setting the IPv6 ECN bits, but that should 
also affect the Sugarland build too.  There's also a few *(__be32*) 
dereferences in net/ipv6/ip6_route.c and net/ipv6/ip6_tunnel.c that are 
new to the 3.6 kernel.  The attached patches should hopefully fix all of 
the new traps.

Robert Bradley

-------------- next part --------------
A non-text attachment was scrubbed...
Name: 924-ecn-alignment-fixes.patch
Type: text/x-patch
Size: 871 bytes
Desc: not available
URL: <https://lists.bufferbloat.net/pipermail/cerowrt-devel/attachments/20121208/c2dbf36c/attachment-0004.bin>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 925-ipv6-alignment-fixes.patch
Type: text/x-patch
Size: 3949 bytes
Desc: not available
URL: <https://lists.bufferbloat.net/pipermail/cerowrt-devel/attachments/20121208/c2dbf36c/attachment-0005.bin>

More information about the Cerowrt-devel mailing list