On 30/11/2019 06:02, Cong Wang wrote:
On Fri, Nov 29, 2019 at 5:24 AM John Garry <[email protected]> wrote:
On 29/11/2019 00:48, Cong Wang wrote:
If the maganize is empty, iova_magazine_free_pfns() should
magazine
Good catch!
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 <[email protected]>
Signed-off-by: Cong Wang <[email protected]>
---
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))
The only hot path we this call is
__iova_rcache_insert()->iova_magazine_free_pfns(mag_to_free) and
mag_to_free is full in this case, so I am sure how the additional check
helps, right?
This is what I mean by "a little bit" in changelog, did you miss it or
misunderstand it? :)
I was concerned that in the fastpath we actually make things very
marginally slower by adding a check which will fail.
Thanks,
John
Thanks.
.
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