cxlflash: Increase cmd_per_lun for better throughput

With the current value of cmd_per_lun at 16, the throughput
over a single adapter is limited to around 150kIOPS.

Increase the value of cmd_per_lun to 256 to improve
throughput. With this change a single adapter is able to
attain close to the maximum throughput (380kIOPS).
Also change the number of RRQ entries that can be queued.

Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
Acked-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Reviewed-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/cxlflash/common.h b/drivers/scsi/cxlflash/common.h
index 5ada926..a8ac4c0 100644 (file)
--- a/drivers/scsi/cxlflash/common.h
+++ b/drivers/scsi/cxlflash/common.h
@@ -34,7 +34,6 @@ extern const struct file_operations cxlflash_cxl_fops;
                                                                   sectors
                                                                */
 
-#define NUM_RRQ_ENTRY    16     /* for master issued cmds */
 #define MAX_RHT_PER_CONTEXT (PAGE_SIZE / sizeof(struct sisl_rht_entry))
 
 /* AFU command retry limit */
@@ -48,9 +47,12 @@ extern const struct file_operations cxlflash_cxl_fops;
                                                           index derivation
                                                         */
 
-#define CXLFLASH_MAX_CMDS               16
+#define CXLFLASH_MAX_CMDS               256
 #define CXLFLASH_MAX_CMDS_PER_LUN       CXLFLASH_MAX_CMDS
 
+/* RRQ for master issued cmds */
+#define NUM_RRQ_ENTRY                   CXLFLASH_MAX_CMDS
+
 
 static inline void check_sizes(void)
 {
@@ -149,7 +151,7 @@ struct afu_cmd {
 struct afu {
        /* Stuff requiring alignment go first. */
 
-       u64 rrq_entry[NUM_RRQ_ENTRY];   /* 128B RRQ */
+       u64 rrq_entry[NUM_RRQ_ENTRY];   /* 2K RRQ */
        /*
         * Command & data for AFU commands.
         */

diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c
index 0f062a4..3879b46 100644 (file)
--- a/drivers/scsi/cxlflash/main.c
+++ b/drivers/scsi/cxlflash/main.c
@@ -2253,7 +2253,7 @@ static struct scsi_host_template driver_template = {
        .eh_device_reset_handler = cxlflash_eh_device_reset_handler,
        .eh_host_reset_handler = cxlflash_eh_host_reset_handler,
        .change_queue_depth = cxlflash_change_queue_depth,
-       .cmd_per_lun = 16,
+       .cmd_per_lun = CXLFLASH_MAX_CMDS_PER_LUN,
        .can_queue = CXLFLASH_MAX_CMDS,
        .this_id = -1,
        .sg_tablesize = SG_NONE,        /* No scatter gather support */