On Thu, Jun 07, 2018 at 04:49:26PM -0700, Matthew Wilcox wrote: > 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"? I would say they are close to equally important, perhaps the version/class/method is slightly more important. > 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. I was wondering about that as well, this code is very old so there must be better data structure helpers these days. Jason -- 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
