TCP loopback socket fusing
Fabien Thomas
fabien.thomas at netasq.com
Tue Sep 14 16:08:37 UTC 2010
On 14 sept. 2010, at 17:41, Andre Oppermann wrote:
> On 14.09.2010 11:18, Fabien Thomas wrote:
>> Great,
>>
>> This will maybe kill the long time debate about "my loopback is slow vs linux"
>> To have the best of both world what about a socket option to enable/disable fusing:
>> can be useful when you need to see some connection "packetized".
>
> A sysctl to that effect is already in the patch.
yes, i'm just wondering on a per connection setting.
>
> --
> Andre
>
>> Fabien
>>
>> On 13 sept. 2010, at 13:33, Andre Oppermann wrote:
>>
>>> When a TCP connection via loopback back to localhost is made the whole
>>> send, segmentation and receive path (with larger packets though) is still
>>> executed. This has some considerable overhead.
>>>
>>> To short-circuit the send and receive sockets on localhost TCP connections
>>> I've made a proof-of-concept patch that directly places the data in the
>>> other side's socket buffer without doing any packetization and other protocol
>>> overhead (like UNIX domain sockets). The connections setup (SYN, SYN-ACK,
>>> ACK) and shutdown are still handled by normal TCP segments via loopback so
>>> that firewalling stills works. The actual payload data during the session
>>> won't be seen and the sequence numbers don't move other than for SYN and FIN.
>>> The sequence are remain valid though. Obviously tcpdump won't see any data
>>> transfers either if the connection has fused sockets.
>>>
>>> Preliminary testing (with WITNESS and INVARIANTS enabled) has shown stable
>>> operation and a rough doubling of the throughput on loopback connections.
>>> I've tested most socket teardown cases and it behaves fine. I'm not entirely
>>> sure I've got all possible path's but the way it is integrated should properly
>>> defuse the sockets in all situations.
>>>
>>> Testers and feedback wanted:
>>>
>>> http://people.freebsd.org/~andre/tcp_loopfuse-20100913.diff
>>>
>>> --
>>> Andre
>>>
>>> _______________________________________________
>>> freebsd-net at freebsd.org mailing list
>>> http://lists.freebsd.org/mailman/listinfo/freebsd-net
>>> To unsubscribe, send any mail to "freebsd-net-unsubscribe at freebsd.org"
>>
>>
>>
>
More information about the freebsd-current
mailing list