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Patch "cxlflash: Increase cmd_per_lun for better throughput" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Mar 22, 2017

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This is a note to let you know that I've just added the patch titled

cxlflash: Increase cmd_per_lun for better throughput

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
cxlflash-increase-cmd_per_lun-for-better-throughput.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 83430833b4d4a9c9b23964babbeb1f36450f8136 Mon Sep 17 00:00:00 2001

From: "Manoj N. Kumar" <[email protected]>
Date: Fri, 4 Mar 2016 15:55:20 -0600
Subject: cxlflash: Increase cmd_per_lun for better throughput

From: Manoj N. Kumar <[email protected]>

commit 83430833b4d4a9c9b23964babbeb1f36450f8136 upstream.

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 <[email protected]>
Acked-by Matthew R. Ochs <[email protected]>
Reviewed-by Uma Krishnan <[email protected]>
Signed-off-by Martin K. Petersen <[email protected]>
Cc Sumit Semwal <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/scsi/cxlflash/common.h |    8 +++++---
 drivers/scsi/cxlflash/main.c   |    2 +-
 2 files changed, 6 insertions(+), 4 deletions(-)
drivers/scsi/cxlflash/common.h +5 -3
@@ -34,7 +34,6 @@ extern const struct file_operations cxlf
 								   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 cxlf
 							   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.
 	 */
drivers/scsi/cxlflash/main.c +1 -1
@@ -2305,7 +2305,7 @@ static struct scsi_host_template driver_
 	.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 */

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/cxlflash-increase-cmd_per_lun-for-better-throughput.patch