On Mon, Sep 27, 2021 at 08:55:19PM +0800, Mark Zhang wrote: > On 9/27/2021 8:24 PM, Jason Gunthorpe wrote: > > External email: Use caution opening links or attachments > > > > > > On Mon, Sep 27, 2021 at 03:09:44PM +0300, Leon Romanovsky wrote: > > > On Sun, Sep 26, 2021 at 05:36:01PM +0000, Chuck Lever III wrote: > > > > Hi Leon- > > > > > > > > Thanks for the suggestion! More below. > > > > > > > > > On Sep 26, 2021, at 4:02 AM, Leon Romanovsky <leon@xxxxxxxxxx> wrote: > > > > > > > > > > On Fri, Sep 24, 2021 at 03:34:32PM +0000, bugzilla-daemon@xxxxxxxxxxxxxxxxxxx wrote: > > > > > > https://bugzilla.kernel.org/show_bug.cgi?id=214523 > > > > > > > > > > > > Bug ID: 214523 > > > > > > Summary: RDMA Mellanox RoCE drivers are unresponsive to ARP > > > > > > updates during a reconnect > > > > > > Product: Drivers > > > > > > Version: 2.5 > > > > > > Kernel Version: 5.14 > > > > > > Hardware: All > > > > > > OS: Linux > > > > > > Tree: Mainline > > > > > > Status: NEW > > > > > > Severity: normal > > > > > > Priority: P1 > > > > > > Component: Infiniband/RDMA > > > > > > Assignee: drivers_infiniband-rdma@xxxxxxxxxxxxxxxxxxxx > > > > > > Reporter: kolga@xxxxxxxxxx > > > > > > Regression: No > > > > > > > > > > > > RoCE RDMA connection uses CMA protocol to establish an RDMA connection. During > > > > > > the setup the code uses hard coded timeout/retry values. These values are used > > > > > > for when Connect Request is not being answered to to re-try the request. During > > > > > > the re-try attempts the ARP updates of the destination server are ignored. > > > > > > Current timeout values lead to 4+minutes long attempt at connecting to a server > > > > > > that no longer owns the IP since the ARP update happens. > > > > > > > > > > > > The ask is to make the timeout/retry values configurable via procfs or sysfs. > > > > > > This will allow for environments that use RoCE to reduce the timeouts to a more > > > > > > reasonable values and be able to react to the ARP updates faster. Other CMA > > > > > > users (eg IB or others) can continue to use existing values. > > > > > > > > I would rather not add a user-facing tunable. The fabric should > > > > be better at detecting addressing changes within a reasonable > > > > time. It would be helpful to provide a history of why the ARP > > > > timeout is so lax -- do certain ULPs rely on it being long? > > > > > > I don't know about ULPs and ARPs, but how to calculate TimeWait is > > > described in the spec. > > > > > > Regarding tunable, I agree. Because it needs to be per-connection, most > > > likely not many people in the world will success to configure it properly. > > > > Maybe we should be disconnecting the cm_id if a gratituous ARP changes > > the MAC address? The cm_id is surely broken after that event right? > > Is there an event on gratuitous ARP? And we also need to notify user-space > application, right? I think there is a net notifier for this? Userspace will see it via the CM event we'll need to trigger. Jason
