iommu/iova: Optimize iova_magazine_alloc()

Zhen Lei · joergroedel · commit 5d62bacc059b · 2023-05-22T17:09:51.000+02:00
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@arm.com> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Link: https://lore.kernel.org/r/20230421072422.869-1-thunder.leizhen@huawei.com Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git 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)

Original file line number	Diff line number	Diff line change
`@@ -647,7 +647,13 @@ struct iova_rcache {`
`647`	`647`
`648`	`648`	`static struct iova_magazine *iova_magazine_alloc(gfp_t flags)`
`649`	`649`	`{`
`650`		`- return kzalloc(sizeof(struct iova_magazine), flags);`
	`650`	`+ struct iova_magazine *mag;`
	`651`	`+`
	`652`	`+ mag = kmalloc(sizeof(*mag), flags);`
	`653`	`+ if (mag)`
	`654`	`+ mag->size = 0;`
	`655`	`+`
	`656`	`+ return mag;`
`651`	`657`	`}`
`652`	`658`
`653`	`659`	`static void iova_magazine_free(struct iova_magazine *mag)`