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From: Cong Wang <xiyou.wangcong@gmail.com>
To: iommu@lists.linux-foundation.org
Cc: linux-kernel@vger.kernel.org, joro@8bytes.org,
	Cong Wang <xiyou.wangcong@gmail.com>
Subject: [Patch v2 2/3] iommu: optimize iova_magazine_free_pfns()
Date: Thu, 28 Nov 2019 16:48:54 -0800	[thread overview]
Message-ID: <20191129004855.18506-3-xiyou.wangcong@gmail.com> (raw)
In-Reply-To: <20191129004855.18506-1-xiyou.wangcong@gmail.com>

If the maganize is empty, iova_magazine_free_pfns() should
be a nop, however it misses the case of mag->size==0. So we
should just call iova_magazine_empty().

This should reduce the contention on iovad->iova_rbtree_lock
a little bit.

Cc: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
---
 drivers/iommu/iova.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index cb473ddce4cf..184d4c0e20b5 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -797,13 +797,23 @@ static void iova_magazine_free(struct iova_magazine *mag)
 	kfree(mag);
 }
 
+static bool iova_magazine_full(struct iova_magazine *mag)
+{
+	return (mag && mag->size == IOVA_MAG_SIZE);
+}
+
+static bool iova_magazine_empty(struct iova_magazine *mag)
+{
+	return (!mag || mag->size == 0);
+}
+
 static void
 iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad)
 {
 	unsigned long flags;
 	int i;
 
-	if (!mag)
+	if (iova_magazine_empty(mag))
 		return;
 
 	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
@@ -820,16 +830,6 @@ iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad)
 	mag->size = 0;
 }
 
-static bool iova_magazine_full(struct iova_magazine *mag)
-{
-	return (mag && mag->size == IOVA_MAG_SIZE);
-}
-
-static bool iova_magazine_empty(struct iova_magazine *mag)
-{
-	return (!mag || mag->size == 0);
-}
-
 static unsigned long iova_magazine_pop(struct iova_magazine *mag,
 				       unsigned long limit_pfn)
 {
-- 
2.21.0


WARNING: multiple messages have this Message-ID (diff)
From: Cong Wang <xiyou.wangcong@gmail.com>
To: iommu@lists.linux-foundation.org
Cc: Cong Wang <xiyou.wangcong@gmail.com>, linux-kernel@vger.kernel.org
Subject: [Patch v2 2/3] iommu: optimize iova_magazine_free_pfns()
Date: Thu, 28 Nov 2019 16:48:54 -0800	[thread overview]
Message-ID: <20191129004855.18506-3-xiyou.wangcong@gmail.com> (raw)
In-Reply-To: <20191129004855.18506-1-xiyou.wangcong@gmail.com>

If the maganize is empty, iova_magazine_free_pfns() should
be a nop, however it misses the case of mag->size==0. So we
should just call iova_magazine_empty().

This should reduce the contention on iovad->iova_rbtree_lock
a little bit.

Cc: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
---
 drivers/iommu/iova.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index cb473ddce4cf..184d4c0e20b5 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -797,13 +797,23 @@ static void iova_magazine_free(struct iova_magazine *mag)
 	kfree(mag);
 }
 
+static bool iova_magazine_full(struct iova_magazine *mag)
+{
+	return (mag && mag->size == IOVA_MAG_SIZE);
+}
+
+static bool iova_magazine_empty(struct iova_magazine *mag)
+{
+	return (!mag || mag->size == 0);
+}
+
 static void
 iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad)
 {
 	unsigned long flags;
 	int i;
 
-	if (!mag)
+	if (iova_magazine_empty(mag))
 		return;
 
 	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
@@ -820,16 +830,6 @@ iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad)
 	mag->size = 0;
 }
 
-static bool iova_magazine_full(struct iova_magazine *mag)
-{
-	return (mag && mag->size == IOVA_MAG_SIZE);
-}
-
-static bool iova_magazine_empty(struct iova_magazine *mag)
-{
-	return (!mag || mag->size == 0);
-}
-
 static unsigned long iova_magazine_pop(struct iova_magazine *mag,
 				       unsigned long limit_pfn)
 {
-- 
2.21.0

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  parent reply	other threads:[~2019-11-29  0:49 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-29  0:48 [Patch v2 0/3] iommu: reduce spinlock contention on fast path Cong Wang
2019-11-29  0:48 ` Cong Wang
2019-11-29  0:48 ` [Patch v2 1/3] iommu: match the original algorithm Cong Wang
2019-11-29  0:48   ` Cong Wang
2019-11-29 14:43   ` John Garry
2019-11-29 14:43     ` John Garry
2019-11-30  5:58     ` Cong Wang
2019-11-30  5:58       ` Cong Wang
2019-12-02 10:55       ` John Garry
2019-12-02 10:55         ` John Garry
2019-12-03 19:26         ` Cong Wang
2019-12-03 19:26           ` Cong Wang
2019-12-02 16:58   ` Christoph Hellwig
2019-12-02 16:58     ` Christoph Hellwig
2019-12-03 19:24     ` Cong Wang
2019-12-03 19:24       ` Cong Wang
2019-11-29  0:48 ` Cong Wang [this message]
2019-11-29  0:48   ` [Patch v2 2/3] iommu: optimize iova_magazine_free_pfns() Cong Wang
2019-11-29 13:24   ` John Garry
2019-11-29 13:24     ` John Garry
2019-11-30  6:02     ` Cong Wang
2019-11-30  6:02       ` Cong Wang
2019-12-02 10:02       ` John Garry
2019-12-02 10:02         ` John Garry
2019-12-03 19:40         ` Cong Wang
2019-12-03 19:40           ` Cong Wang
2019-12-02 16:59   ` Christoph Hellwig
2019-12-02 16:59     ` Christoph Hellwig
2019-12-03 19:28     ` Cong Wang
2019-12-03 19:28       ` Cong Wang
2019-11-29  0:48 ` [Patch v2 3/3] iommu: avoid taking iova_rbtree_lock twice Cong Wang
2019-11-29  0:48   ` Cong Wang
2019-11-29 13:34   ` John Garry
2019-11-29 13:34     ` John Garry
2019-11-30  6:03     ` Cong Wang
2019-11-30  6:03       ` Cong Wang
2019-12-17  9:43 ` [Patch v2 0/3] iommu: reduce spinlock contention on fast path Joerg Roedel
2019-12-17  9:43   ` Joerg Roedel
2019-12-18  4:32   ` Cong Wang
2019-12-18  4:32     ` Cong Wang

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