IB/iser: Use IB_WR_REG_MR_INTEGRITY for PI handover

Using this new API reduces iSER code complexity.
It also reduces the maximum number of work requests per task and the need
of dealing with multiple MRs (and their registrations and invalidations)
per task. It is done by using a single WR and a special MR type
(IB_MR_TYPE_INTEGRITY) for PI operation.

The setup of the tested benchmark:
 - 2 servers with 24 cores (1 initiator and 1 target)
 - 24 target sessions with 1 LUN each
 - ramdisk backstore
 - PI active

Performance results running fio (24 jobs, 128 iodepth) using
write_generate=0 and read_verify=0 (w/w.o patch):

bs      IOPS(read)        IOPS(write)
----    ----------        ----------
512     1236.6K/1164.3K   1357.2K/1332.8K
1k      1196.5K/1163.8K   1348.4K/1262.7K
2k      1016.7K/921950    1003.7K/931230
4k      662728/600545     595423/501513
8k      385954/384345     333775/277090
16k     222864/222820     170317/170671
32k     116869/114896     82331/82244
64k     55205/54931       40264/40021

Using write_generate=1 and read_verify=1 (w/w.o patch):

bs      IOPS(read)        IOPS(write)
----    ----------        ----------
512     1090.1K/1030.9K   1303.9K/1101.4K
1k      1057.7K/904583    1318.4K/988085
2k      965226/638799     1008.6K/692514
4k      555479/410151     542414/414517
8k      298675/224964     264729/237508
16k     133485/122481     164625/138647
32k     74329/67615       80143/78743
64k     35716/35519       39294/37334

We get performance improvement at all block sizes.
The most significant improvement is when writing 4k bs (almost 30% more
iops).

Signed-off-by: Israel Rukshin <israelr@mellanox.com>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 8 insertions, 30 deletions

diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.h b/drivers/infiniband/ulp/iser/iscsi_iser.h
index 36d525110fd2..6bf9eaa8ec96 100644
--- a/drivers/infiniband/ulp/iser/iscsi_iser.h
+++ b/drivers/infiniband/ulp/iser/iscsi_iser.h
@@ -225,13 +225,11 @@ enum iser_desc_type {
 	ISCSI_TX_DATAOUT
 };
 
-/* Maximum number of work requests per task:
- * Data memory region local invalidate + fast registration
- * Protection memory region local invalidate + fast registration
- * Signature memory region local invalidate + fast registration
- * PDU send
+/*
+ * Maximum number of work requests per task
+ * (invalidate, registration, send)
  */
-#define ISER_MAX_WRS 7
+#define ISER_MAX_WRS 3
 
 /**
  * struct iser_tx_desc - iSER TX descriptor
@@ -247,9 +245,6 @@ enum iser_desc_type {
  * @mapped:        Is the task header mapped
  * @wr_idx:        Current WR index
  * @wrs:           Array of WRs per task
- * @data_reg:      Data buffer registration details
- * @prot_reg:      Protection buffer registration details
- * @sig_attrs:     Signature attributes
  */
 struct iser_tx_desc {
 	struct iser_ctrl             iser_header;
@@ -264,11 +259,7 @@ struct iser_tx_desc {
 	union iser_wr {
 		struct ib_send_wr		send;
 		struct ib_reg_wr		fast_reg;
-		struct ib_sig_handover_wr	sig;
 	} wrs[ISER_MAX_WRS];
-	struct iser_mem_reg          data_reg;
-	struct iser_mem_reg          prot_reg;
-	struct ib_sig_attrs          sig_attrs;
 };
 
 #define ISER_RX_PAD_SIZE	(256 - (ISER_RX_PAYLOAD_SIZE + \
@@ -388,6 +379,7 @@ struct iser_device {
  *
  * @mr:         memory region
  * @fmr_pool:   pool of fmrs
+ * @sig_mr:     signature memory region
  * @page_vec:   fast reg page list used by fmr pool
  * @mr_valid:   is mr valid indicator
  */
@@ -396,36 +388,22 @@ struct iser_reg_resources {
 		struct ib_mr             *mr;
 		struct ib_fmr_pool       *fmr_pool;
 	};
+	struct ib_mr                     *sig_mr;
 	struct iser_page_vec             *page_vec;
 	u8				  mr_valid:1;
 };
 
 /**
- * struct iser_pi_context - Protection information context
- *
- * @rsc:             protection buffer registration resources
- * @sig_mr:          signature enable memory region
- * @sig_mr_valid:    is sig_mr valid indicator
- * @sig_protected:   is region protected indicator
- */
-struct iser_pi_context {
-	struct iser_reg_resources	rsc;
-	struct ib_mr                   *sig_mr;
-	u8                              sig_mr_valid:1;
-	u8                              sig_protected:1;
-};
-
-/**
  * struct iser_fr_desc - Fast registration descriptor
  *
  * @list:           entry in connection fastreg pool
  * @rsc:            data buffer registration resources
- * @pi_ctx:         protection information context
+ * @sig_protected:  is region protected indicator
  */
 struct iser_fr_desc {
 	struct list_head		  list;
 	struct iser_reg_resources	  rsc;
-	struct iser_pi_context		 *pi_ctx;
+	bool				  sig_protected;
 	struct list_head                  all_list;
 };