Date: Sun, 15 Mar 2009 20:17:44 +0000 (UTC) From: Robert Watson <rwatson@FreeBSD.org> To: cvs-src-old@freebsd.org Subject: cvs commit: src/share/man/man4 lo.4 src/sys/net if_loop.c Message-ID: <200903152023.n2FKNPbD065450@repoman.freebsd.org>
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rwatson 2009-03-15 20:17:44 UTC
FreeBSD src repository
Modified files:
share/man/man4 lo.4
sys/net if_loop.c
Log:
SVN rev 189863 on 2009-03-15 20:17:44Z by rwatson
Teach the loopback interface about checksum generation and validation
avoidance:
- Enable setting the RXCSUM and TXCSUM flags for loopback interfaces;
set both by default.
- When RXCSUM is set, flag packets sent over the loopback interface as
having checked and valid IP, UDP, TCP checksums so that higher
protocol layers won't check them.
- Always clear CSUM_{IP,UDP_TCP} checksum required flags on transmit,
as they will have gotten there as a result of TXCSUM being set.
This is done only for packets explicitly sent over the loopback, not
simulated loopback via if_simloop() due to !SIMPLEX interfaces, etc.
Note that enabling TXCSUM but not RXCSUM will lead to unhappiness, as
checksums won't be generated but will be validated.
Kris reports that this leads to significant performance improvements
in loopback benchmarking with TCP and UDP for throughput:
RXCSUM RXCSUM+TXCSUM
TCP 15% 37%
UDP 10% 74%
Update man page.
Reviewed by: sam
Tested by: kris
MFC after: 1 week
Revision Changes Path
1.10 +21 -12 src/share/man/man4/lo.4
1.126 +22 -1 src/sys/net/if_loop.c
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