Re: [PATCH] RDMA/iw_cxgb4: disable delayed ack by default

[Leon Romanovsky <leon@kernel.org>]

On Thu, Sep 10, 2020 at 07:14:50PM +0000, Potnuri Bharat Teja wrote:
> >> Subject: [PATCH] RDMA/iw_cxgb4: disable delayed ack by default
> >>
> >> Receive side delayed ack mode is needed only for certain area networks/ connections. Therefore disable it by default.
> >>
> >> Signed-off-by: Potnuri Bharat Teja <bharat@chelsio.com>
> >> ---
> >>  drivers/infiniband/hw/cxgb4/cm.c | 4 ++--
> >>  1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
> >> index 1f288c73ccfc..8769e7aa097f 100644
> >> --- a/drivers/infiniband/hw/cxgb4/cm.c
> >> +++ b/drivers/infiniband/hw/cxgb4/cm.c
> >> @@ -77,9 +77,9 @@ static int enable_ecn;  module_param(enable_ecn, int, 0644);  MODULE_PARM_DESC(enable_ecn, "Enable ECN (default=0/disabled)");
> >>
> >> -static int dack_mode = 1;
> >> +static int dack_mode;
> >>  module_param(dack_mode, int, 0644);
> >> -MODULE_PARM_DESC(dack_mode, "Delayed ack mode (default=1)");
> >> +MODULE_PARM_DESC(dack_mode, "Delayed ack mode (default=0)");
> >
> >Are you sure that this doesn't break user scripts?
> Yes, I am sure. This does not interfere with user/kernel RDMA functionalities.

How is it possible?
Before this change user that did "modprobe iw_cxgb4" had delayed mode
enabled, after this he will need to issue "modprobe iw_cxgb4 dack_mode=1"

https://github.com/linux-rdma/rdma-core/blob/master/kernel-boot/rdma-hw-modules.rules#L12

Thanks

>
> Thanks,
> Bharat.
> >
> >Thanks
> >
> >>
> >>  uint c4iw_max_read_depth = 32;
> >>  module_param(c4iw_max_read_depth, int, 0644);
> >> --
> >> 2.24.0