mbox series

[net-next,v3,0/2] net/smc: Fix effective buffer size

Message ID 20230804163049.937185-1-gbayer@linux.ibm.com
Headers
Series net/smc: Fix effective buffer size |

Message

Gerd Bayer Aug. 4, 2023, 4:30 p.m. UTC 
  Hi all,

commit 0227f058aa29 ("net/smc: Unbind r/w buffer size from clcsock
and make them tunable") started to derive the effective buffer size for
SMC connections inconsistently in case a TCP fallback was used and
memory consumption of SMC with the default settings was doubled when
a connection negotiated SMC. That was not what we want.

This series consolidates the resulting effective buffer size that is
used with SMC sockets, which is based on Jan Karcher's effort (see 
[1]). For all TCP exchanges (in particular in case of a fall back when
no SMC connection was possible) the values from net.ipv4.tcp_[rw]mem
are used. If SMC succeeds in establishing a SMC connection, the newly
introduced values from net.smc.[rw]mem are used.

net.smc.[rw]mem is initialized to 64kB, respectively. Internal test 
have show this to be a good compromise between throughput/latency 
and memory consumption. Also net.smc.[rw]mem is now decoupled completely
from any tuning through net.ipv4.tcp_[rw]mem.

If a user chose to tune a socket's receive or send buffer size with
setsockopt, this tuning is now consistently applied to either fall-back
TCP or proper SMC connections over the socket.

Thanks,
Gerd 

v2 - v3:
 - Rebase to and resolve conflict of second patch with latest net/master.
v1 - v2:
 - In second patch, use sock_net() helper as suggested by Tony and demanded
   by kernel test robot.


Gerd Bayer (2):
  net/smc: Fix setsockopt and sysctl to specify same buffer size again
  net/smc: Use correct buffer sizes when switching between TCP and SMC

 net/smc/af_smc.c     | 77 ++++++++++++++++++++++++++++++--------------
 net/smc/smc.h        |  2 +-
 net/smc/smc_clc.c    |  4 +--
 net/smc/smc_core.c   | 25 +++++++-------
 net/smc/smc_sysctl.c | 10 ++++--
 5 files changed, 76 insertions(+), 42 deletions(-)


base-commit: 1733d0be68ab1b89358a3b0471ef425fd61de7c5

Comments

Jakub Kicinski Aug. 4, 2023, 8:41 p.m. UTC | #1 
On Fri, 04 Aug 2023 18:55:26 +0200 Gerd Bayer wrote:
> this should have gone as v3 against "net" instead of "net-next".
> Resending ASAP.
> 
> Sorry for the noise,

Less apologizing more reading of the rules, please.

https://www.kernel.org/doc/html/next/process/maintainer-netdev.html