ib_isert: Add support for completion interrupt coalescing
This patch adds support for completion interrupt coalescing that allows only every ISERT_COMP_BATCH_COUNT (8) to set IB_SEND_SIGNALED, thus avoiding completion interrupts for every posted iser_tx_desc. The batch processing is done using a per isert_conn llist that once IB_SEND_SIGNALED has been set is saved to tx_desc->comp_llnode_batch, and completion processing of previously posted iser_tx_descs is done in a single shot from within isert_send_completion() code. Note this is only done for response PDUs from ISCSI_OP_SCSI_CMD, and all other control type of PDU responses will force an implicit batch drain to occur. Cc: Or Gerlitz <ogerlitz@mellanox.com> Cc: Sagi Grimberg <sagig@mellanox.com> Cc: Kent Overstreet <kmo@daterainc.com> Cc: Roland Dreier <roland@purestorage.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>hifive-unleashed-5.1
Nicholas Bellinger
parent
2dd1d53fe0
commit
95b60f0788
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@ -22,6 +22,7 @@
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#include <linux/socket.h>
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#include <linux/in.h>
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#include <linux/in6.h>
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#include <linux/llist.h>
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#include <rdma/ib_verbs.h>
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#include <rdma/rdma_cm.h>
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#include <target/target_core_base.h>
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@ -489,6 +490,7 @@ isert_connect_request(struct rdma_cm_id *cma_id, struct rdma_cm_event *event)
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kref_init(&isert_conn->conn_kref);
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kref_get(&isert_conn->conn_kref);
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mutex_init(&isert_conn->conn_mutex);
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mutex_init(&isert_conn->conn_comp_mutex);
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spin_lock_init(&isert_conn->conn_lock);
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cma_id->context = isert_conn;
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@ -843,14 +845,32 @@ isert_init_tx_hdrs(struct isert_conn *isert_conn,
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}
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static void
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isert_init_send_wr(struct isert_cmd *isert_cmd, struct ib_send_wr *send_wr)
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isert_init_send_wr(struct isert_conn *isert_conn, struct isert_cmd *isert_cmd,
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struct ib_send_wr *send_wr, bool coalesce)
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{
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struct iser_tx_desc *tx_desc = &isert_cmd->tx_desc;
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isert_cmd->rdma_wr.iser_ib_op = ISER_IB_SEND;
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send_wr->wr_id = (unsigned long)&isert_cmd->tx_desc;
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send_wr->opcode = IB_WR_SEND;
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send_wr->send_flags = IB_SEND_SIGNALED;
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send_wr->sg_list = &isert_cmd->tx_desc.tx_sg[0];
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send_wr->sg_list = &tx_desc->tx_sg[0];
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send_wr->num_sge = isert_cmd->tx_desc.num_sge;
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/*
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* Coalesce send completion interrupts by only setting IB_SEND_SIGNALED
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* bit for every ISERT_COMP_BATCH_COUNT number of ib_post_send() calls.
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*/
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mutex_lock(&isert_conn->conn_comp_mutex);
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if (coalesce &&
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++isert_conn->conn_comp_batch < ISERT_COMP_BATCH_COUNT) {
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llist_add(&tx_desc->comp_llnode, &isert_conn->conn_comp_llist);
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mutex_unlock(&isert_conn->conn_comp_mutex);
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return;
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}
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isert_conn->conn_comp_batch = 0;
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tx_desc->comp_llnode_batch = llist_del_all(&isert_conn->conn_comp_llist);
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mutex_unlock(&isert_conn->conn_comp_mutex);
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send_wr->send_flags = IB_SEND_SIGNALED;
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}
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static int
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@ -1582,8 +1602,8 @@ isert_response_completion(struct iser_tx_desc *tx_desc,
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}
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static void
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isert_send_completion(struct iser_tx_desc *tx_desc,
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struct isert_conn *isert_conn)
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__isert_send_completion(struct iser_tx_desc *tx_desc,
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struct isert_conn *isert_conn)
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{
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struct ib_device *ib_dev = isert_conn->conn_cm_id->device;
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struct isert_cmd *isert_cmd = tx_desc->isert_cmd;
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@ -1623,6 +1643,24 @@ isert_send_completion(struct iser_tx_desc *tx_desc,
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}
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}
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static void
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isert_send_completion(struct iser_tx_desc *tx_desc,
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struct isert_conn *isert_conn)
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{
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struct llist_node *llnode = tx_desc->comp_llnode_batch;
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struct iser_tx_desc *t;
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/*
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* Drain coalesced completion llist starting from comp_llnode_batch
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* setup in isert_init_send_wr(), and then complete trailing tx_desc.
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*/
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while (llnode) {
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t = llist_entry(llnode, struct iser_tx_desc, comp_llnode);
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llnode = llist_next(llnode);
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__isert_send_completion(t, isert_conn);
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}
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__isert_send_completion(tx_desc, isert_conn);
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}
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static void
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isert_cq_comp_err(struct iser_tx_desc *tx_desc, struct isert_conn *isert_conn)
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{
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@ -1793,7 +1831,7 @@ isert_put_response(struct iscsi_conn *conn, struct iscsi_cmd *cmd)
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isert_cmd->tx_desc.num_sge = 2;
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}
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isert_init_send_wr(isert_cmd, send_wr);
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isert_init_send_wr(isert_conn, isert_cmd, send_wr, true);
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pr_debug("Posting SCSI Response IB_WR_SEND >>>>>>>>>>>>>>>>>>>>>>\n");
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@ -1813,7 +1851,7 @@ isert_put_nopin(struct iscsi_cmd *cmd, struct iscsi_conn *conn,
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&isert_cmd->tx_desc.iscsi_header,
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nopout_response);
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isert_init_tx_hdrs(isert_conn, &isert_cmd->tx_desc);
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isert_init_send_wr(isert_cmd, send_wr);
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isert_init_send_wr(isert_conn, isert_cmd, send_wr, false);
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pr_debug("Posting NOPIN Response IB_WR_SEND >>>>>>>>>>>>>>>>>>>>>>\n");
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@ -1831,7 +1869,7 @@ isert_put_logout_rsp(struct iscsi_cmd *cmd, struct iscsi_conn *conn)
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iscsit_build_logout_rsp(cmd, conn, (struct iscsi_logout_rsp *)
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&isert_cmd->tx_desc.iscsi_header);
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isert_init_tx_hdrs(isert_conn, &isert_cmd->tx_desc);
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isert_init_send_wr(isert_cmd, send_wr);
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isert_init_send_wr(isert_conn, isert_cmd, send_wr, false);
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pr_debug("Posting Logout Response IB_WR_SEND >>>>>>>>>>>>>>>>>>>>>>\n");
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@ -1849,7 +1887,7 @@ isert_put_tm_rsp(struct iscsi_cmd *cmd, struct iscsi_conn *conn)
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iscsit_build_task_mgt_rsp(cmd, conn, (struct iscsi_tm_rsp *)
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&isert_cmd->tx_desc.iscsi_header);
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isert_init_tx_hdrs(isert_conn, &isert_cmd->tx_desc);
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isert_init_send_wr(isert_cmd, send_wr);
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isert_init_send_wr(isert_conn, isert_cmd, send_wr, false);
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pr_debug("Posting Task Management Response IB_WR_SEND >>>>>>>>>>>>>>>>>>>>>>\n");
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@ -1881,7 +1919,7 @@ isert_put_reject(struct iscsi_cmd *cmd, struct iscsi_conn *conn)
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tx_dsg->lkey = isert_conn->conn_mr->lkey;
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isert_cmd->tx_desc.num_sge = 2;
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isert_init_send_wr(isert_cmd, send_wr);
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isert_init_send_wr(isert_conn, isert_cmd, send_wr, false);
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pr_debug("Posting Reject IB_WR_SEND >>>>>>>>>>>>>>>>>>>>>>\n");
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@ -1921,7 +1959,7 @@ isert_put_text_rsp(struct iscsi_cmd *cmd, struct iscsi_conn *conn)
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tx_dsg->lkey = isert_conn->conn_mr->lkey;
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isert_cmd->tx_desc.num_sge = 2;
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}
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isert_init_send_wr(isert_cmd, send_wr);
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isert_init_send_wr(isert_conn, isert_cmd, send_wr, false);
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pr_debug("Posting Text Response IB_WR_SEND >>>>>>>>>>>>>>>>>>>>>>\n");
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@ -2309,7 +2347,8 @@ isert_put_datain(struct iscsi_conn *conn, struct iscsi_cmd *cmd)
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iscsit_build_rsp_pdu(cmd, conn, false, (struct iscsi_scsi_rsp *)
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&isert_cmd->tx_desc.iscsi_header);
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isert_init_tx_hdrs(isert_conn, &isert_cmd->tx_desc);
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isert_init_send_wr(isert_cmd, &isert_cmd->tx_desc.send_wr);
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isert_init_send_wr(isert_conn, isert_cmd,
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&isert_cmd->tx_desc.send_wr, true);
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atomic_inc(&isert_conn->post_send_buf_count);
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@ -43,6 +43,8 @@ struct iser_tx_desc {
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struct ib_sge tx_sg[2];
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int num_sge;
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struct isert_cmd *isert_cmd;
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struct llist_node *comp_llnode_batch;
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struct llist_node comp_llnode;
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struct ib_send_wr send_wr;
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} __packed;
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@ -121,6 +123,10 @@ struct isert_conn {
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int conn_frwr_pool_size;
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/* lock to protect frwr_pool */
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spinlock_t conn_lock;
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#define ISERT_COMP_BATCH_COUNT 8
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int conn_comp_batch;
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struct llist_head conn_comp_llist;
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struct mutex conn_comp_mutex;
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};
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#define ISERT_MAX_CQ 64
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