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SubjectRe: [PATCH 0/4] Optimise 64-bit IOVA allocations
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On 2017/7/19 18:23, Robin Murphy wrote:
> On 19/07/17 09:37, Ard Biesheuvel wrote:
>> On 18 July 2017 at 17:57, Robin Murphy <robin.murphy@arm.com> wrote:
>>> Hi all,
>>>
>>> In the wake of the ARM SMMU optimisation efforts, it seems that certain
>>> workloads (e.g. storage I/O with large scatterlists) probably remain quite
>>> heavily influenced by IOVA allocation performance. Separately, Ard also
>>> reported massive performance drops for a graphical desktop on AMD Seattle
>>> when enabling SMMUs via IORT, which we traced to dma_32bit_pfn in the DMA
>>> ops domain getting initialised differently for ACPI vs. DT, and exposing
>>> the overhead of the rbtree slow path. Whilst we could go around trying to
>>> close up all the little gaps that lead to hitting the slowest case, it
>>> seems a much better idea to simply make said slowest case a lot less slow.
>>>
>>> I had a go at rebasing Leizhen's last IOVA series[1], but ended up finding
>>> the changes rather too hard to follow, so I've taken the liberty here of
>>> picking the whole thing up and reimplementing the main part in a rather
>>> less invasive manner.
>>>
>>> Robin.
>>>
>>> [1] https://www.mail-archive.com/iommu@lists.linux-foundation.org/msg17753.html
>>>
>>> Robin Murphy (1):
>>> iommu/iova: Extend rbtree node caching
>>>
>>> Zhen Lei (3):
>>> iommu/iova: Optimise rbtree searching
>>> iommu/iova: Optimise the padding calculation
>>> iommu/iova: Make dma_32bit_pfn implicit
>>>
>>> drivers/gpu/drm/tegra/drm.c | 3 +-
>>> drivers/gpu/host1x/dev.c | 3 +-
>>> drivers/iommu/amd_iommu.c | 7 +--
>>> drivers/iommu/dma-iommu.c | 18 +------
>>> drivers/iommu/intel-iommu.c | 11 ++--
>>> drivers/iommu/iova.c | 112 ++++++++++++++++-----------------------
>>> drivers/misc/mic/scif/scif_rma.c | 3 +-
>>> include/linux/iova.h | 8 +--
>>> 8 files changed, 60 insertions(+), 105 deletions(-)
>>>
>>
>> These patches look suspiciously like the ones I have been using over
>> the past couple of weeks (modulo the tegra and host1x changes) from
>> your git tree. They work fine on my AMD Overdrive B1, both in DT and
>> in ACPI/IORT modes, although it is difficult to quantify any
>> performance deltas on my setup.
>
> Indeed - this is a rebase (to account for those new callers) with a
> couple of trivial tweaks to error paths and corner cases that normal
> usage shouldn't have been hitting anyway. "No longer unusably awful" is
> a good enough performance delta for me :)
>
>> Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
I got the same performance data compared with my patch version. It works well.

Tested-by: Zhen Lei <thunder.leizhen@huawei.com>

>
> Thanks!
>
> Robin.
>
> .
>

--
Thanks!
BestRegards

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