-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 22.08.2013 00:51, Andre Oppermann wrote: > On 19.08.2013 13:42, Alexander V. Chernikov wrote: >> On 14.08.2013 19:48, Luigi Rizzo wrote: >>> On Wed, Aug 14, 2013 at 05:40:28PM +0200, Marko Zec wrote: >>>> On Wednesday 14 August 2013 14:40:24 Luigi Rizzo wrote: >>>>> On Wed, Aug 14, 2013 at 04:15:25PM +0400, Alexander V. >>>>> Chernikov wrote: >>> ... >>>> FWIW, apparently we already have that infrastrucure in place >>>> - if_rele() calls if_free_internal() only when the last >>>> reference to the ifnet is dropped, so with little care this >>>> should be usable for caching ifp pointers w/o fears for >>>> kernel crashes mentioned above. >>> maybe Alexander was referring to holding references to the rte >>> entries returned as a result of the lookup. The rte holds a >>> reference to the ifp. >> >> Yes. Since there is the only refcount which is protected (and is >> also a huge performance killer). >> >> Btw, there is a picture describing IPv4 packet flow from my >> still-not-written post related network stack performance, maybe >> it can be useful: >> http://static.ipfw.ru/images/freebsd_ipv4_flow.png > > Wow, that's really cool. Please note that a rmlock doesn't cost > anything for the read case (unless contended of course). Whereas > normal rlocks or We're running this entire stack without singe rwlock (everything is either converted to rmlock or using lockless data copies with delayed GC (in_adrr_local and other similar)). It really is fasters, but, however, due to current process-to-completion routing architecture this is limited to 5-6MPPS for 12 cores on 2xE5645.
> rwlocks write to the lock memory location and cause atomic bus lock > cycles as well as a lot of cache line invalidations across cores. > The same is true for refcounts. > -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.20 (FreeBSD) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlIYq7QACgkQwcJ4iSZ1q2nFZwCfZLckg4b/iny2CK+bYJa20XxE y7UAnRZHVr4AZRYnB8acrN54KtRMpvNQ =0kPb -----END PGP SIGNATURE----- _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
