diff options
| author | Robin Murphy <robin.murphy@arm.com> | 2017-09-28 12:31:23 +0200 |
|---|---|---|
| committer | Joerg Roedel <jroedel@suse.de> | 2017-09-28 14:57:16 +0200 |
| commit | e8b198402745ed413ed8229b2eb45d34016eb5d8 (patch) | |
| tree | 4b552a320579484b7f0e8e5ada98c97e2832d12f | |
| parent | iommu/iova: Make rcache limit_pfn handling more robust (diff) | |
| download | linux-e8b198402745ed413ed8229b2eb45d34016eb5d8.tar.xz linux-e8b198402745ed413ed8229b2eb45d34016eb5d8.zip | |
iommu/iova: Try harder to allocate from rcache magazine
When devices with different DMA masks are using the same domain, or for
PCI devices where we usually try a speculative 32-bit allocation first,
there is a fair possibility that the top PFN of the rcache stack at any
given time may be unsuitable for the lower limit, prompting a fallback
to allocating anew from the rbtree. Consequently, we may end up
artifically increasing pressure on the 32-bit IOVA space as unused IOVAs
accumulate lower down in the rcache stacks, while callers with 32-bit
masks also impose unnecessary rbtree overhead.
In such cases, let's try a bit harder to satisfy the allocation locally
first - scanning the whole stack should still be relatively inexpensive.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
| -rw-r--r-- | drivers/iommu/iova.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c index 15ff3033bbd7..b0ca23682008 100644 --- a/drivers/iommu/iova.c +++ b/drivers/iommu/iova.c @@ -821,12 +821,21 @@ static bool iova_magazine_empty(struct iova_magazine *mag) static unsigned long iova_magazine_pop(struct iova_magazine *mag, unsigned long limit_pfn) { + int i; + unsigned long pfn; + BUG_ON(iova_magazine_empty(mag)); - if (mag->pfns[mag->size - 1] > limit_pfn) - return 0; + /* Only fall back to the rbtree if we have no suitable pfns at all */ + for (i = mag->size - 1; mag->pfns[i] > limit_pfn; i--) + if (i == 0) + return 0; + + /* Swap it to pop it */ + pfn = mag->pfns[i]; + mag->pfns[i] = mag->pfns[--mag->size]; - return mag->pfns[--mag->size]; + return pfn; } static void iova_magazine_push(struct iova_magazine *mag, unsigned long pfn) |