From: Nicholas Bellinger Date: Tue, 5 Nov 2013 21:16:12 +0000 (-0800) Subject: ib_isert: Add support for completion interrupt coalescing X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=95b60f0;p=linux-beck.git 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 Cc: Sagi Grimberg Cc: Kent Overstreet Cc: Roland Dreier Signed-off-by: Nicholas Bellinger --- diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c index 3591855cc5b5..27708c3430d5 100644 --- a/drivers/infiniband/ulp/isert/ib_isert.c +++ b/drivers/infiniband/ulp/isert/ib_isert.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include #include @@ -489,6 +490,7 @@ isert_connect_request(struct rdma_cm_id *cma_id, struct rdma_cm_event *event) kref_init(&isert_conn->conn_kref); kref_get(&isert_conn->conn_kref); mutex_init(&isert_conn->conn_mutex); + mutex_init(&isert_conn->conn_comp_mutex); spin_lock_init(&isert_conn->conn_lock); cma_id->context = isert_conn; @@ -843,14 +845,32 @@ isert_init_tx_hdrs(struct isert_conn *isert_conn, } static void -isert_init_send_wr(struct isert_cmd *isert_cmd, struct ib_send_wr *send_wr) +isert_init_send_wr(struct isert_conn *isert_conn, struct isert_cmd *isert_cmd, + struct ib_send_wr *send_wr, bool coalesce) { + struct iser_tx_desc *tx_desc = &isert_cmd->tx_desc; + isert_cmd->rdma_wr.iser_ib_op = ISER_IB_SEND; send_wr->wr_id = (unsigned long)&isert_cmd->tx_desc; send_wr->opcode = IB_WR_SEND; - send_wr->send_flags = IB_SEND_SIGNALED; - send_wr->sg_list = &isert_cmd->tx_desc.tx_sg[0]; + send_wr->sg_list = &tx_desc->tx_sg[0]; send_wr->num_sge = isert_cmd->tx_desc.num_sge; + /* + * Coalesce send completion interrupts by only setting IB_SEND_SIGNALED + * bit for every ISERT_COMP_BATCH_COUNT number of ib_post_send() calls. + */ + mutex_lock(&isert_conn->conn_comp_mutex); + if (coalesce && + ++isert_conn->conn_comp_batch < ISERT_COMP_BATCH_COUNT) { + llist_add(&tx_desc->comp_llnode, &isert_conn->conn_comp_llist); + mutex_unlock(&isert_conn->conn_comp_mutex); + return; + } + isert_conn->conn_comp_batch = 0; + tx_desc->comp_llnode_batch = llist_del_all(&isert_conn->conn_comp_llist); + mutex_unlock(&isert_conn->conn_comp_mutex); + + send_wr->send_flags = IB_SEND_SIGNALED; } static int @@ -1582,8 +1602,8 @@ isert_response_completion(struct iser_tx_desc *tx_desc, } static void -isert_send_completion(struct iser_tx_desc *tx_desc, - struct isert_conn *isert_conn) +__isert_send_completion(struct iser_tx_desc *tx_desc, + struct isert_conn *isert_conn) { struct ib_device *ib_dev = isert_conn->conn_cm_id->device; struct isert_cmd *isert_cmd = tx_desc->isert_cmd; @@ -1623,6 +1643,24 @@ isert_send_completion(struct iser_tx_desc *tx_desc, } } +static void +isert_send_completion(struct iser_tx_desc *tx_desc, + struct isert_conn *isert_conn) +{ + struct llist_node *llnode = tx_desc->comp_llnode_batch; + struct iser_tx_desc *t; + /* + * Drain coalesced completion llist starting from comp_llnode_batch + * setup in isert_init_send_wr(), and then complete trailing tx_desc. + */ + while (llnode) { + t = llist_entry(llnode, struct iser_tx_desc, comp_llnode); + llnode = llist_next(llnode); + __isert_send_completion(t, isert_conn); + } + __isert_send_completion(tx_desc, isert_conn); +} + static void isert_cq_comp_err(struct iser_tx_desc *tx_desc, struct isert_conn *isert_conn) { @@ -1793,7 +1831,7 @@ isert_put_response(struct iscsi_conn *conn, struct iscsi_cmd *cmd) isert_cmd->tx_desc.num_sge = 2; } - isert_init_send_wr(isert_cmd, send_wr); + isert_init_send_wr(isert_conn, isert_cmd, send_wr, true); pr_debug("Posting SCSI Response IB_WR_SEND >>>>>>>>>>>>>>>>>>>>>>\n"); @@ -1813,7 +1851,7 @@ isert_put_nopin(struct iscsi_cmd *cmd, struct iscsi_conn *conn, &isert_cmd->tx_desc.iscsi_header, nopout_response); isert_init_tx_hdrs(isert_conn, &isert_cmd->tx_desc); - isert_init_send_wr(isert_cmd, send_wr); + isert_init_send_wr(isert_conn, isert_cmd, send_wr, false); pr_debug("Posting NOPIN Response IB_WR_SEND >>>>>>>>>>>>>>>>>>>>>>\n"); @@ -1831,7 +1869,7 @@ isert_put_logout_rsp(struct iscsi_cmd *cmd, struct iscsi_conn *conn) iscsit_build_logout_rsp(cmd, conn, (struct iscsi_logout_rsp *) &isert_cmd->tx_desc.iscsi_header); isert_init_tx_hdrs(isert_conn, &isert_cmd->tx_desc); - isert_init_send_wr(isert_cmd, send_wr); + isert_init_send_wr(isert_conn, isert_cmd, send_wr, false); pr_debug("Posting Logout Response IB_WR_SEND >>>>>>>>>>>>>>>>>>>>>>\n"); @@ -1849,7 +1887,7 @@ isert_put_tm_rsp(struct iscsi_cmd *cmd, struct iscsi_conn *conn) iscsit_build_task_mgt_rsp(cmd, conn, (struct iscsi_tm_rsp *) &isert_cmd->tx_desc.iscsi_header); isert_init_tx_hdrs(isert_conn, &isert_cmd->tx_desc); - isert_init_send_wr(isert_cmd, send_wr); + isert_init_send_wr(isert_conn, isert_cmd, send_wr, false); pr_debug("Posting Task Management Response IB_WR_SEND >>>>>>>>>>>>>>>>>>>>>>\n"); @@ -1881,7 +1919,7 @@ isert_put_reject(struct iscsi_cmd *cmd, struct iscsi_conn *conn) tx_dsg->lkey = isert_conn->conn_mr->lkey; isert_cmd->tx_desc.num_sge = 2; - isert_init_send_wr(isert_cmd, send_wr); + isert_init_send_wr(isert_conn, isert_cmd, send_wr, false); pr_debug("Posting Reject IB_WR_SEND >>>>>>>>>>>>>>>>>>>>>>\n"); @@ -1921,7 +1959,7 @@ isert_put_text_rsp(struct iscsi_cmd *cmd, struct iscsi_conn *conn) tx_dsg->lkey = isert_conn->conn_mr->lkey; isert_cmd->tx_desc.num_sge = 2; } - isert_init_send_wr(isert_cmd, send_wr); + isert_init_send_wr(isert_conn, isert_cmd, send_wr, false); pr_debug("Posting Text Response IB_WR_SEND >>>>>>>>>>>>>>>>>>>>>>\n"); @@ -2309,7 +2347,8 @@ isert_put_datain(struct iscsi_conn *conn, struct iscsi_cmd *cmd) iscsit_build_rsp_pdu(cmd, conn, false, (struct iscsi_scsi_rsp *) &isert_cmd->tx_desc.iscsi_header); isert_init_tx_hdrs(isert_conn, &isert_cmd->tx_desc); - isert_init_send_wr(isert_cmd, &isert_cmd->tx_desc.send_wr); + isert_init_send_wr(isert_conn, isert_cmd, + &isert_cmd->tx_desc.send_wr, true); atomic_inc(&isert_conn->post_send_buf_count); diff --git a/drivers/infiniband/ulp/isert/ib_isert.h b/drivers/infiniband/ulp/isert/ib_isert.h index 631f2090f0b8..691f90ff2d83 100644 --- a/drivers/infiniband/ulp/isert/ib_isert.h +++ b/drivers/infiniband/ulp/isert/ib_isert.h @@ -43,6 +43,8 @@ struct iser_tx_desc { struct ib_sge tx_sg[2]; int num_sge; struct isert_cmd *isert_cmd; + struct llist_node *comp_llnode_batch; + struct llist_node comp_llnode; struct ib_send_wr send_wr; } __packed; @@ -121,6 +123,10 @@ struct isert_conn { int conn_frwr_pool_size; /* lock to protect frwr_pool */ spinlock_t conn_lock; +#define ISERT_COMP_BATCH_COUNT 8 + int conn_comp_batch; + struct llist_head conn_comp_llist; + struct mutex conn_comp_mutex; }; #define ISERT_MAX_CQ 64