IB/srp: consolidate hot-path variables into cache lines

Put the variables accessed together in the hot-path into common
cachelines, and separate them by RW vs RO to avoid false dirtying.
We keep a local copy of the lkey and rkey in the target to avoid
traversing pointers (and associated cache lines) to find them.

Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: David Dillow <dillowda@ornl.gov>

2 files changed, 26 insertions, 17 deletions

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 8691fc83f70b..4b62105ed1e8 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -768,7 +768,7 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
                 struct srp_direct_buf *buf = (void *) cmd->add_data;
 
                 buf->va  = cpu_to_be64(ib_sg_dma_address(ibdev, scat));
-                buf->key = cpu_to_be32(dev->mr->rkey);
+                buf->key = cpu_to_be32(target->rkey);
                 buf->len = cpu_to_be32(ib_sg_dma_len(ibdev, scat));
         } else if (srp_map_fmr(target, scat, count, req,
                                (void *) cmd->add_data)) {
@@ -793,7 +793,7 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
                         buf->desc_list[i].va  =
                                 cpu_to_be64(ib_sg_dma_address(ibdev, sg));
                         buf->desc_list[i].key =
-                                cpu_to_be32(dev->mr->rkey);
+                                cpu_to_be32(target->rkey);
                         buf->desc_list[i].len = cpu_to_be32(dma_len);
                         datalen += dma_len;
                 }
@@ -806,7 +806,7 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
                 buf->table_desc.va  =
                         cpu_to_be64(req->cmd->dma + sizeof *cmd + sizeof *buf);
                 buf->table_desc.key =
-                        cpu_to_be32(target->srp_host->srp_dev->mr->rkey);
+                        cpu_to_be32(target->rkey);
                 buf->table_desc.len =
                         cpu_to_be32(count * sizeof (struct srp_direct_buf));
 
@@ -883,7 +883,7 @@ static int srp_post_send(struct srp_target_port *target,
 
         list.addr   = iu->dma;
         list.length = len;
-        list.lkey   = target->srp_host->srp_dev->mr->lkey;
+        list.lkey   = target->lkey;
 
         wr.next       = NULL;
         wr.wr_id      = (uintptr_t) iu;
@@ -902,7 +902,7 @@ static int srp_post_recv(struct srp_target_port *target, struct srp_iu *iu)
 
         list.addr   = iu->dma;
         list.length = iu->size;
-        list.lkey   = target->srp_host->srp_dev->mr->lkey;
+        list.lkey   = target->lkey;
 
         wr.next     = NULL;
         wr.wr_id    = (uintptr_t) iu;
@@ -1955,6 +1955,8 @@ static ssize_t srp_create_target(struct device *dev,
         target->io_class   = SRP_REV16A_IB_IO_CLASS;
         target->scsi_host  = target_host;
         target->srp_host   = host;
+        target->lkey       = host->srp_dev->mr->lkey;
+        target->rkey       = host->srp_dev->mr->rkey;
 
         spin_lock_init(&target->lock);
         INIT_LIST_HEAD(&target->free_tx);
diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index acb435d3c1e3..9dc6fc3fd894 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -117,6 +117,24 @@ struct srp_request {
 };
 
 struct srp_target_port {
+        /* These are RW in the hot path, and commonly used together */
+        struct list_head        free_tx;
+        struct list_head        free_reqs;
+        spinlock_t              lock;
+        s32                     req_lim;
+
+        /* These are read-only in the hot path */
+        struct ib_cq           *send_cq ____cacheline_aligned_in_smp;
+        struct ib_cq           *recv_cq;
+        struct ib_qp           *qp;
+        u32                     lkey;
+        u32                     rkey;
+        enum srp_target_state   state;
+
+        /* Everything above this point is used in the hot path of
+         * command processing. Try to keep them packed into cachelines.
+         */
+
         __be64                  id_ext;
         __be64                  ioc_guid;
         __be64                  service_id;
@@ -133,23 +151,13 @@ struct srp_target_port {
         int                     path_query_id;
 
         struct ib_cm_id        *cm_id;
-        struct ib_cq           *recv_cq;
-        struct ib_cq           *send_cq;
-        struct ib_qp           *qp;
 
         int                     max_ti_iu_len;
-        s32                     req_lim;
 
         int                     zero_req_lim;
 
-        struct srp_iu          *rx_ring[SRP_RQ_SIZE];
-
-        spinlock_t              lock;
-
-        struct list_head        free_tx;
         struct srp_iu          *tx_ring[SRP_SQ_SIZE];
-
-        struct list_head        free_reqs;
+        struct srp_iu          *rx_ring[SRP_RQ_SIZE];
         struct srp_request      req_ring[SRP_CMD_SQ_SIZE];
 
         struct work_struct      work;
@@ -157,7 +165,6 @@ struct srp_target_port {
         struct list_head        list;
         struct completion       done;
         int                     status;
-        enum srp_target_state   state;
         int                     qp_in_error;
 
         struct completion       tsk_mgmt_done;