[PATCH 0/7] Increase maximum Infiniband HCAs per-system

Alex Chiang
2010-01-29T21:45:17Z

Justin Chen discovered that Linux "only" supports 32 IB cards in
a single system when testing a larger system with 40 cards and
discovered that OFED only reported 32 HCAs.

This patchset doubles the number of HCAs allowed per system in a
backwards-compatible manner.

Why only double? Well, it keeps the implementation very simple while
also keeping the memory increase at a minimum. If the future
requires even more HCAs per system, we can do a more complicated
implementation then.

I tested this by inserting 4 IB cards into a system, and then
changing IB_UVERBS_MAX_DEVICES = 2.

dl585g2:~ # modprobe ib_uverbs
dl585g2:~ # ls -l /dev/uverbs*
crw-rw---- 1 root root 231, 192 Jan 28 06:59 /dev/uverbs0
crw-rw---- 1 root root 231, 193 Jan 28 06:59 /dev/uverbs1
crw-rw---- 1 root root 249, 0 Jan 28 06:59 /dev/uverbs2
crw-rw---- 1 root root 249, 1 Jan 28 06:59 /dev/uverbs3

You can see that the uverbs devices are numbered in order, as one
would expect, and that devices 2 and 3 have different major numbers
while devices 0 and 1 retain the legacy, allocated major number.

I don't have access to a huge system to really test what
happens at device 33, but it should just work, right? :)

I am also unaware of any OFED changes required (if that's even
necessary), but then again, I'm just a simple kernel guy.

The final two patches are just something I discovered while using
pahole to verify my changes in converting the *cdev pointer to an
embedded struct. They don't save all that much, but they also don't
change very much code either, so why not?

Thanks,
/ac

---

Alex Chiang (7):
IB/uverbs: convert *cdev to cdev in struct ib_uverbs_device
IB/uverbs: remove dev_table
IB/uverbs: use stack variable 'devnum' in ib_uverbs_add_one
IB/uverbs: use stack variable 'base' in ib_uverbs_add_one
IB/uverbs: increase maximum devices supported
IB/uverbs: pack struct ib_uverbs_event_file tighter
IB/core: pack struct ib_device a little tighter

drivers/infiniband/core/uverbs.h | 11 ++-
drivers/infiniband/core/uverbs_main.c | 106 +++++++++++++++++++++------------
include/rdma/ib_verbs.h | 4 +
3 files changed, 76 insertions(+), 45 deletions(-)