On 5/25/2012 12:20 PM, Venkat Venkatsubra wrote:
On 5/24/2012 7:18 PM, Hefty, Sean wrote:
We are trying to figure out the cause for RDMA_CM_EVENT_ROUTE_ERROR
errors after a failover event of the bonding driver.
The event status returned is -EINVAL. To gather further information on
when this EINVAL is returned,
I added some debug which showed 3 for mad_hdr.status in the below
function in drivers/infiniband/core/sa_query.c.
[drivers/infiniband/core/sa_query.c]
static void recv_handler(struct ib_mad_agent *mad_agent, struct
ib_mad_recv_wc *mad_recv_wc)
{
struct ib_sa_query *query;
struct ib_mad_send_buf *mad_buf;
mad_buf = (void *) (unsigned long) mad_recv_wc->wc->wr_id;
query = mad_buf->context[0];
if (query->callback) {
if (mad_recv_wc->wc->status == IB_WC_SUCCESS) {
query->callback(query,
mad_recv_wc->recv_buf.mad->mad_hdr.status ? -EINVAL : 0,
(struct ib_sa_mad *)
mad_recv_wc->recv_buf.mad);
How do I find out what 3 in mad_recv_wc->recv_buf.mad->mad_hdr.status
stands for ?
You would need to look in the IB spec. Note that the status field is
16-bits and should be in big endian order. Assuming, therefore, that
the '3' falls into the upper bits of the status field, this would be
an SA specific status value of ERR_NO_RECORDS.
Yes, it is 0x300. My display was in little endian order.
To test RDS reconnect time we are rebooting one of the switch connected
to one port of the bonding driver.
It then fails over to the other port, RDMA CM gets notified which then
notifies RDS.
RDS initiates a reconnect. rdma_resolve_route results in these
errors.
There are some 25 connections that try to failover at the same time.
We get this error for a couple of seconds and finally the
rdma_resolve_route succeeds.
Some of them succeed right away. So it may be due to the load generated
by too many rdma_resolve_route.
You may need to back up and see what rdma_resolve_addr returns in the
cases where rdma_resolve_route fails, and compare that with
rdma_resolve_addr when rdma_resolve_route succeeds. Maybe there's be
a timing issue with the SA detecting the switch failure. Can you
tell if the RDS traffic is actually migrating to the new ports?
Ok. I will check what rdma_resolve_addr returns and compare it with a
successful case.
Some other connections completed successfully over the new port during
the same period and traffic did go through successfully over them.
-Sean
Venkat
rdma_resolve_addr returned the old GID for the destination IP during
these rdma_resolve_route failures.
Then we found the arp entry for these destination IPs continued pointing
to the old GID and did not get updated with the failed over GID.
Aren't they supposed to be updated through gratuitous arp on a failover
? Looks like some entries did not get updated.
Anyway this is a missing arp entry update issue now. Nothing to do with
rdma_resolve_*. ping over ipoib also shows the same failure.
For testing purpose we tried flushing the arp table right after the
failover so that arp requests go out right away and relearn the new GID.
That worked fine.
Venkat
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