RDMA/cxgb3: Doorbell overflow avoidance and recovery
T3 hardware doorbell FIFO overflows can cause application stalls due
to lost doorbell ring events. This has been seen when running large
NP IMB alltoall MPI jobs. The T3 hardware supports an xon/xoff-type
flow control mechanism to help avoid overflowing the HW doorbell FIFO.
This patch uses these interrupts to disable RDMA QP doorbell rings
when we near an overflow condition, and then turn them back on (and
ring all the active QP doorbells) when when the doorbell FIFO empties
out. In addition if an doorbell ring is dropped by the hardware, the
code will now recover.
Design:
cxgb3:
- enable these DB interrupts
- in the interrupt handler, schedule work tasks to call the ULPs event
handlers with the new events.
- ring all the qset txqs when an overflow is detected.
iw_cxgb3:
- disable db ringing on all active qps when we get the DB_FULL event
- enable db ringing on all active qps and ring all active dbs when we get
the DB_EMPTY event
- On DB_DROP event:
- disable db rings in the event handler
- delay-schedule a work task which rings and enables the dbs on
all active qps.
- in post_send and post_recv logic, don't ring the db if it's disabled.
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/net/cxgb3/regs.h b/drivers/net/cxgb3/regs.h
index 1b5327b..cb42353 100644
--- a/drivers/net/cxgb3/regs.h
+++ b/drivers/net/cxgb3/regs.h
@@ -254,6 +254,22 @@
#define V_LOPIODRBDROPERR(x) ((x) << S_LOPIODRBDROPERR)
#define F_LOPIODRBDROPERR V_LOPIODRBDROPERR(1U)
+#define S_HIPRIORITYDBFULL 7
+#define V_HIPRIORITYDBFULL(x) ((x) << S_HIPRIORITYDBFULL)
+#define F_HIPRIORITYDBFULL V_HIPRIORITYDBFULL(1U)
+
+#define S_HIPRIORITYDBEMPTY 6
+#define V_HIPRIORITYDBEMPTY(x) ((x) << S_HIPRIORITYDBEMPTY)
+#define F_HIPRIORITYDBEMPTY V_HIPRIORITYDBEMPTY(1U)
+
+#define S_LOPRIORITYDBFULL 5
+#define V_LOPRIORITYDBFULL(x) ((x) << S_LOPRIORITYDBFULL)
+#define F_LOPRIORITYDBFULL V_LOPRIORITYDBFULL(1U)
+
+#define S_LOPRIORITYDBEMPTY 4
+#define V_LOPRIORITYDBEMPTY(x) ((x) << S_LOPRIORITYDBEMPTY)
+#define F_LOPRIORITYDBEMPTY V_LOPRIORITYDBEMPTY(1U)
+
#define S_RSPQDISABLED 3
#define V_RSPQDISABLED(x) ((x) << S_RSPQDISABLED)
#define F_RSPQDISABLED V_RSPQDISABLED(1U)