From 6cfd9e62e3297993f9f9d2d15f3acb14a0e8abbf Mon Sep 17 00:00:00 2001
From: Dave Jiang <dave.jiang@intel.com>
Date: Thu, 24 Jun 2021 13:39:33 -0700
Subject: [PATCH] dmaengine: idxd: assign MSIX vectors to each WQ rather than roundrobin
Git-commit: 6cfd9e62e3297993f9f9d2d15f3acb14a0e8abbf
Patch-mainline: v5.15-rc1
References: jsc#SLE-18899

IOPS increased when changing MSIX vector to per WQ from roundrobin.
Allows descriptor to be completed by the submitter improves caching
locality.

Suggested-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Link: https://lore.kernel.org/r/162456717326.1130457.15258077196523268356.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/dma/idxd/idxd.h   |    2 --
 drivers/dma/idxd/submit.c |   22 +++++++---------------
 2 files changed, 7 insertions(+), 17 deletions(-)

--- a/drivers/dma/idxd/idxd.h
+++ b/drivers/dma/idxd/idxd.h
@@ -153,7 +153,6 @@ struct idxd_wq {
 	enum idxd_wq_state state;
 	unsigned long flags;
 	union wqcfg *wqcfg;
-	u32 vec_ptr;		/* interrupt steering */
 	struct dsa_hw_desc **hw_descs;
 	int num_descs;
 	union {
@@ -290,7 +289,6 @@ struct idxd_desc {
 	struct list_head list;
 	int id;
 	int cpu;
-	unsigned int vector;
 	struct idxd_wq *wq;
 };
 
--- a/drivers/dma/idxd/submit.c
+++ b/drivers/dma/idxd/submit.c
@@ -22,21 +22,13 @@ static struct idxd_desc *__get_desc(stru
 		desc->hw->pasid = idxd->pasid;
 
 	/*
-	 * Descriptor completion vectors are 1...N for MSIX. We will round
-	 * robin through the N vectors.
+	 * On host, MSIX vecotr 0 is used for misc interrupt. Therefore when we match
+	 * vector 1:1 to the WQ id, we need to add 1
 	 */
-	wq->vec_ptr = desc->vector = (wq->vec_ptr % idxd->num_wq_irqs) + 1;
-	if (!idxd->int_handles) {
-		desc->hw->int_handle = wq->vec_ptr;
-	} else {
-		/*
-		 * int_handles are only for descriptor completion. However for device
-		 * MSIX enumeration, vec 0 is used for misc interrupts. Therefore even
-		 * though we are rotating through 1...N for descriptor interrupts, we
-		 * need to acqurie the int_handles from 0..N-1.
-		 */
-		desc->hw->int_handle = idxd->int_handles[desc->vector - 1];
-	}
+	if (!idxd->int_handles)
+		desc->hw->int_handle = wq->id + 1;
+	else
+		desc->hw->int_handle = idxd->int_handles[wq->id];
 
 	return desc;
 }
@@ -168,7 +160,7 @@ int idxd_submit_desc(struct idxd_wq *wq,
 	 * that we designated the descriptor to.
 	 */
 	if (desc->hw->flags & IDXD_OP_FLAG_RCI) {
-		ie = &idxd->irq_entries[desc->vector];
+		ie = &idxd->irq_entries[wq->id + 1];
 		llist_add(&desc->llnode, &ie->pending_llist);
 	}