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iommu/iova: Extend rbtree node caching

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The cached node mechanism provides a significant performance benefit for
allocations using a 32-bit DMA mask, but in the case of non-PCI devices
or where the 32-bit space is full, the loss of this benefit can be
significant - on large systems there can be many thousands of entries in
the tree, such that walking all the way down to find free space every
time becomes increasingly awful.

Maintain a similar cached node for the whole IOVA space as a superset of
the 32-bit space so that performance can remain much more consistent.

Inspired by work by Zhen Lei <thunder.leizhen@huawei.com>.

Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Zhen Lei <thunder.leizhen@huawei.com>
Tested-by: Nate Watterson <nwatters@codeaurora.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Robin Murphy 2017-09-21 16:52:44 +01:00 • committed by Joerg Roedel
parent 086c83acb7
commit e60aa7b538
2 changed files with 30 additions and 33 deletions
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3
include/linux/iova.h
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@ -70,7 +70,8 @@ struct iova_fq {
struct iova_domain {
spinlock_t iova_rbtree_lock; /* Lock to protect update of rbtree */
struct rb_root rbroot; /* iova domain rbtree root */
struct rb_node *cached32_node; /* Save last alloced node */
struct rb_node *cached_node; /* Save last alloced node */
struct rb_node *cached32_node; /* Save last 32-bit alloced node */
unsigned long granule; /* pfn granularity for this domain */
unsigned long start_pfn; /* Lower limit for this domain */
unsigned long dma_32bit_pfn;