On Thu, Jun 07, 2018 at 04:26:46PM -0600, Jason Gunthorpe wrote: > On Thu, Jun 07, 2018 at 12:08:32PM -0700, Matthew Wilcox wrote: > > > > Hans reports a bug where the mlx4 driver uses the MSB of the agent number > > to store slave number, meaning we can only use agent numbers up to 2^24. > > Fix this by using an IDR to assign the agent numbers and also look up the > > agent when a MSD packet is received. > > > > I've changed the locking substantially, so this may well have a > > performance issue. There are a few different possibilities for fixing > > that, including moving to an RCU-based lookup. > > I do like this better than the last series.. > > This are is somewhat performance sensitive and it would be nice to > avoid this global lock. OK, I wasn't sure whether it was worth it. > What about using a read/write spinlock instead of the IDR internal > lock? Then all the per-port reading threads calling find_mad_agent can > run concurrently.. It'd be better to switch to RCU ... the IDR is RCU-safe, but the version/class/method or OUI match isn't. Do you have any feeling on the relative frequency of the two types of "routing"? Actually, I think we can use the radix tree data structure for the version/class/method too ... that's going to take a little more work. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
