On Tue, Apr 02, 2024 at 12:50:21PM +0300, Leon Romanovsky wrote: > From: Michael Guralnik <michaelgur@xxxxxxxxxx> > > ib_umad is keeping the received MAD packets in a list that is not > limited in size. As the extraction of packets from this list is done > from user-space application, there is no way to guarantee the extraction > rate to be faster than the rate of incoming packets. This can cause to > the list to grow uncontrollably. > > As a solution, let's add new ysfs control knob for the users to limit > the number of received MAD packets in the list. > > Packets received when the list is full would be dropped. Sent packets > that are queued on the receive list for whatever reason, like timed out > sends, are not dropped even when the list is full. > > Signed-off-by: Michael Guralnik <michaelgur@xxxxxxxxxx> > Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx> > --- > .../ABI/stable/sysfs-class-infiniband | 12 ++++ > drivers/infiniband/core/user_mad.c | 63 ++++++++++++++++++- > 2 files changed, 72 insertions(+), 3 deletions(-) > > diff --git a/Documentation/ABI/stable/sysfs-class-infiniband b/Documentation/ABI/stable/sysfs-class-infiniband > index 694f23a03a28..0ea9d590ab0e 100644 > --- a/Documentation/ABI/stable/sysfs-class-infiniband > +++ b/Documentation/ABI/stable/sysfs-class-infiniband > @@ -275,6 +275,18 @@ Description: > =============== =========================================== > > > +What: /sys/class/infiniband_mad/umad<N>/max_recv_list_size > +Date: January, 2024 > +KernelVersion: v6.9 > +Contact: linux-rdma@xxxxxxxxxxxxxxx > +Description: > + (RW) Limit the size of the list of MAD packets waiting to be > + read by the user-space agent. > + The default value is 0, which means unlimited list size. > + Packets received when the list is full will be silently > + dropped. I'm really not keen on this as a tunable, when we get to future designs it may be hard to retain this specific behavior. Why do we need a tunable? Can we just set it to something large and be done with it? Jason
