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 1/3] iommu: match the original algorithm
Date: Wed, 20 Nov 2019 16:13:46 -0800 [thread overview]
Message-ID: <20191121001348.27230-2-xiyou.wangcong@gmail.com> (raw)
In-Reply-To: <20191121001348.27230-1-xiyou.wangcong@gmail.com>
The IOVA cache algorithm implemented in IOMMU code does not
exactly match the original algorithm described in the paper.
Particularly, it doesn't need to free the loaded empty magazine
when trying to put it back to global depot.
This patch makes it exactly match the original algorithm.
Cc: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
---
drivers/iommu/iova.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index 41c605b0058f..92f72a85e62a 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -900,7 +900,7 @@ static bool __iova_rcache_insert(struct iova_domain *iovad,
if (!iova_magazine_full(cpu_rcache->loaded)) {
can_insert = true;
- } else if (!iova_magazine_full(cpu_rcache->prev)) {
+ } else if (iova_magazine_empty(cpu_rcache->prev)) {
swap(cpu_rcache->prev, cpu_rcache->loaded);
can_insert = true;
} else {
@@ -909,8 +909,9 @@ static bool __iova_rcache_insert(struct iova_domain *iovad,
if (new_mag) {
spin_lock(&rcache->lock);
if (rcache->depot_size < MAX_GLOBAL_MAGS) {
- rcache->depot[rcache->depot_size++] =
- cpu_rcache->loaded;
+ swap(rcache->depot[rcache->depot_size], cpu_rcache->prev);
+ swap(cpu_rcache->prev, cpu_rcache->loaded);
+ rcache->depot_size++;
} else {
mag_to_free = cpu_rcache->loaded;
}
@@ -963,14 +964,15 @@ static unsigned long __iova_rcache_get(struct iova_rcache *rcache,
if (!iova_magazine_empty(cpu_rcache->loaded)) {
has_pfn = true;
- } else if (!iova_magazine_empty(cpu_rcache->prev)) {
+ } else if (iova_magazine_full(cpu_rcache->prev)) {
swap(cpu_rcache->prev, cpu_rcache->loaded);
has_pfn = true;
} else {
spin_lock(&rcache->lock);
if (rcache->depot_size > 0) {
- iova_magazine_free(cpu_rcache->loaded);
- cpu_rcache->loaded = rcache->depot[--rcache->depot_size];
+ swap(rcache->depot[rcache->depot_size - 1], cpu_rcache->prev);
+ swap(cpu_rcache->prev, cpu_rcache->loaded);
+ rcache->depot_size--;
has_pfn = true;
}
spin_unlock(&rcache->lock);
--
2.21.0
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next prev parent reply other threads:[~2019-11-21 0:26 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-21 0:13 [PATCH 0/3] iommu: reduce spinlock contention on fast path Cong Wang
2019-11-21 0:13 ` Cong Wang [this message]
2019-11-27 18:00 ` [PATCH 1/3] iommu: match the original algorithm John Garry
2019-11-27 18:38 ` Qian Cai
2019-11-28 19:30 ` Cong Wang
2019-11-21 0:13 ` [PATCH 2/3] iommu: optimize iova_magazine_free_pfns() Cong Wang
2019-11-21 0:13 ` [PATCH 3/3] iommu: avoid taking iova_rbtree_lock twice Cong Wang
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