Re: anyone ever done multicast AF_UNIX sockets?

From: Chris Friesen (cfriesen@nortelnetworks.com)
Date: Mon Mar 03 2003 - 16:32:56 EST


Terje Eggestad wrote:
> On Mon, 2003-03-03 at 19:56, David S. Miller wrote:

> TCP bandwidth is slightly faster than AF_UNIX bandwidth on my
> sparc64 boxes for example.
>
> I've seen that their are the same on linux.I tried to to do AF_UNIX
> instead of AF_INET internally to boost perf, but to no avail. Makes you
> suspect that the loopback device actually create an AF_UNIX connection
> under the hood ;-)

On my P4 1.8GHz, AF_INET vs AF_UNIX looks like this:

*Local* Communication latencies in microseconds - smaller is better
-------------------------------------------------------------
Host OS 2p/0K Pipe AF UDP RPC/ TCP RPC/ TCP
                   ctxsw UNIX UDP TCP conn
--------- ------- ----- ----- ---- ----- ----- ----- ----- ----
pcard0ks. 2.4.18- 1.740 10.4 15.9 20.1 33.1 23.5 44.3 72.7
pcard0ks. 2.4.18- 1.560 10.6 16.0 23.4 38.1 36.1 44.6 77.4

*Local* Communication bandwidths in MB/s - bigger is better
-----------------------------------------------------------
Host OS Pipe AF TCP File Mmap Bcopy Bcopy Mem Mem
                        UNIX reread reread (libc) (hand) read write
--------- ------- ---- ---- ---- ------ ------ ------ ------ ---- -----
pcard0ks. 2.4.18- 650. 677. 151. 721.9 958.0 290.8 288.8 955. 418.4
pcard0ks. 2.4.18- 379. 701. 163. 714.8 949.5 289.5 288.5 956. 420.5

On this machine at least, UDP latency is 25% worse than AF_UNIX, and TCP
bandwidth is about 22% that of AF_UNIX.

Chris

-- 
Chris Friesen                    | MailStop: 043/33/F10
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