staging/rdma/hfi1: Adaptive PIO for short messages
The change requires a new pio_busy field in the iowait structure to
track the number of outstanding pios. The new counter together
with the sdma counter serve as the basis for a packet by packet decision
as to which egress mechanism to use. Since packets given to different
egress mechanisms are not ordered, this scheme will preserve the order.
The iowait drain/wait mechanisms are extended for a pio case. An
additional qp wait flag is added for the PIO drain wait case.
Currently the only pio wait is for buffers, so the no_bufs_available()
routine name is changed to pio_wait() and a third argument is passed
with one of the two pio wait flags to generalize the routine. A module
parameter is added to hold a configurable threshold. For now, the
module parameter is zero.
A heuristic routine is added to return the func pointer of the proper
egress routine to use.
The heuristic is as follows:
- SMI always uses pio
- GSI,UD qps <= threshold use pio
- UD qps > threadhold use sdma
o No coordination with sdma is required because order is not required
and this qp pio count is not maintained for UD
- RC/UC ONLY packets <= threshold chose as follows:
o If sdmas pending, use SDMA
o Otherwise use pio and enable the pio tracking count at
the time the pio buffer is allocated
- RC/UC ONLY packets > threshold use SDMA
o If pio's are pending the pio_wait with the new wait flag is
called to delay for pios to drain
The threshold is potentially reduced by the QP's mtu.
The sc_buffer_alloc() has two additional args (a callback, a void *)
which are exploited by the RC/UC cases to pass a new complete routine
and a qp *.
When the shadow ring completes the credit associated with a packet,
the new complete routine is called. The verbs_pio_complete() will then
decrement the busy count and trigger any drain waiters in qp destroy
or reset.
Reviewed-by: Jubin John <jubin.john@intel.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
diff --git a/drivers/staging/rdma/hfi1/hfi.h b/drivers/staging/rdma/hfi1/hfi.h
index 702723b..43d4861 100644
--- a/drivers/staging/rdma/hfi1/hfi.h
+++ b/drivers/staging/rdma/hfi1/hfi.h
@@ -811,6 +811,7 @@
#define BOARD_VERS_MAX 96 /* how long the version string can be */
#define SERIAL_MAX 16 /* length of the serial number */
+typedef int (*send_routine)(struct rvt_qp *, struct hfi1_pkt_state *, u64);
struct hfi1_devdata {
struct hfi1_ibdev verbs_dev; /* must be first */
struct list_head list;
@@ -1121,10 +1122,8 @@
* Handlers for outgoing data so that snoop/capture does not
* have to have its hooks in the send path
*/
- int (*process_pio_send)(struct rvt_qp *qp, struct hfi1_pkt_state *ps,
- u64 pbc);
- int (*process_dma_send)(struct rvt_qp *qp, struct hfi1_pkt_state *ps,
- u64 pbc);
+ send_routine process_pio_send;
+ send_routine process_dma_send;
void (*pio_inline_send)(struct hfi1_devdata *dd, struct pio_buf *pbuf,
u64 pbc, const void *from, size_t count);