netdev - [PATCH net 7/7] ionic: Re-arrange ionic_intr

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Message-ID: <20231201000519.13363-8-shannon.nelson@amd.com>
Date: Thu, 30 Nov 2023 16:05:19 -0800
From: Shannon Nelson <shannon.nelson@....com>
To: <netdev@...r.kernel.org>, <davem@...emloft.net>, <kuba@...nel.org>,
	<edumazet@...gle.com>, <pabeni@...hat.com>
CC: <brett.creeley@....com>, <drivers@...sando.io>, Shannon Nelson
	<shannon.nelson@....com>
Subject: [PATCH net 7/7] ionic: Re-arrange ionic_intr_info struct for cache perf

From: Brett Creeley <brett.creeley@....com>

dim_coal_hw is accessed in the hotpath along with other values
from the first cacheline of ionic_intr_info. So, re-arrange
the structure so the hot path variables are on the first
cacheline.

Before:

struct ionic_intr_info {
	char                       name[32];             /*     0    32 */
	unsigned int               index;                /*    32     4 */
	unsigned int               vector;               /*    36     4 */
	u64                        rearm_count;          /*    40     8 */
	unsigned int               cpu;                  /*    48     4 */

	/* XXX 4 bytes hole, try to pack */

	cpumask_t                  affinity_mask;        /*    56  1024 */
	/* --- cacheline 16 boundary (1024 bytes) was 56 bytes ago --- */
	u32                        dim_coal_hw;          /*  1080     4 */

	/* size: 1088, cachelines: 17, members: 7 */
	/* sum members: 1080, holes: 1, sum holes: 4 */
	/* padding: 4 */
};

After:

struct ionic_intr_info {
	char                       name[32];             /*     0    32 */
	u64                        rearm_count;          /*    32     8 */
	unsigned int               index;                /*    40     4 */
	unsigned int               vector;               /*    44     4 */
	unsigned int               cpu;                  /*    48     4 */
	u32                        dim_coal_hw;          /*    52     4 */
	cpumask_t                  affinity_mask;        /*    56  1024 */

	/* size: 1080, cachelines: 17, members: 7 */
	/* last cacheline: 56 bytes */
};


Fixes: 04a834592bf5 ("ionic: dynamic interrupt moderation")
Signed-off-by: Brett Creeley <brett.creeley@....com>
Signed-off-by: Shannon Nelson <shannon.nelson@....com>
---
 drivers/net/ethernet/pensando/ionic/ionic_dev.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/pensando/ionic/ionic_dev.h b/drivers/net/ethernet/pensando/ionic/ionic_dev.h
index 745a3292be92..c47c059465ae 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_dev.h
+++ b/drivers/net/ethernet/pensando/ionic/ionic_dev.h
@@ -269,12 +269,12 @@ struct ionic_queue {
 
 struct ionic_intr_info {
 	char name[IONIC_INTR_NAME_MAX_SZ];
+	u64 rearm_count;
 	unsigned int index;
 	unsigned int vector;
-	u64 rearm_count;
 	unsigned int cpu;
-	cpumask_t affinity_mask;
 	u32 dim_coal_hw;
+	cpumask_t affinity_mask;
 };
 
 struct ionic_cq {
-- 
2.17.1