linux-kernel - [PATCH v2] iommu/iova: Optimize iova_magazine

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Date:   Fri, 21 Apr 2023 15:24:21 +0800
From:   Zhen Lei <thunder.leizhen@...wei.com>
To:     Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        <iommu@...ts.linux.dev>, <linux-kernel@...r.kernel.org>
CC:     Zhen Lei <thunder.leizhen@...wei.com>
Subject: [PATCH v2] iommu/iova: Optimize iova_magazine_alloc()

Only the member 'size' needs to be initialized to 0. Clearing the array
pfns[], which is about 1 KiB in size, not only wastes time, but also
causes cache pollution.

Acked-by: Robin Murphy <robin.murphy@....com>
Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
---
 drivers/iommu/iova.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

v1 --> v2:
Change sizeof(struct iova_magazine) to sizeof(*mag).

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index fe452ce466429a7..10b964600948c7f 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -647,7 +647,13 @@ struct iova_rcache {
 
 static struct iova_magazine *iova_magazine_alloc(gfp_t flags)
 {
-	return kzalloc(sizeof(struct iova_magazine), flags);
+	struct iova_magazine *mag;
+
+	mag = kmalloc(sizeof(*mag), flags);
+	if (mag)
+		mag->size = 0;
+
+	return mag;
 }
 
 static void iova_magazine_free(struct iova_magazine *mag)
-- 
2.25.1