kernel - network adjustments (netisr, tcp, and socket buffer changes)

Operating Systems / DragonFlyBSD - Matthew Dillon [apollo.backplane.com] - 18 July 2014 01:52 UTC

- Change sowakeup() to use an atomic fetch when testing WAIT/WAKEUP for a quick return. It is now coded properly. Previous coding is not known to have created any bugs.

- Change sowakeup() to use ssb_space_prealloc() instead of ssb_space() when testing against the transmit low-water mark. This is a bug fix which primarily effects very tiny write()'s. The prior code is not known to have created any problems.

- Make the netisr packet counter before doing a rollup programmer and change the default from 512 to 32 for the moment. This may be changed back to 512 (or some number inbetween) after further testing.

The issue here is that interrupt/netisr pipelining can cause ack aggregation to be delayed for too many packets.

- For TCP, when timestamps are not being used, pass the correct delta to tcp_xmit_timer() in our fallback. The function expects N+1. This should improve/fix incorrect rtt calculations when tcp timestamps are not in use.

- Fix an edge case in tcp_xmit_bandwidth_limit() where the 'ticks' global could change values out from under the code. Load the global into a local
variable.

- Change the inflight code to use (t_srtt + t_rttvar) instead of (t_srtt + t_rttbest) / 2.

This needs fine-tuning, the buffer is still too big. Expect more commits later.

- Call sowwakeup() when appending a mbuf to a stream. The append can call sbcompress() and make a stream buffer that has hit its mbuf limit writable again.

- Remove the ssb_notify() macro and collapse the sorwakeup() and sowwakeup() macros. They now just call sowakeup() on the appropriate sockbuf. The notify test is now done in sowakeup().

b210f45 kernel - network adjustments (netisr, tcp, and socket buffer changes)
sys/kern/uipc_socket2.c | 17 +++++++++++++++--
sys/net/netisr.c | 6 +++++-
sys/netinet/tcp_input.c | 22 ++++++++++++----------
sys/netinet/tcp_subr.c | 14 +++++++-------
sys/netinet/tcp_usrreq.c | 4 +++-
sys/sys/socketvar.h | 26 ++------------------------
6 files changed, 44 insertions(+), 45 deletions(-)

Upstream: gitweb.dragonflybsd.org

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