[v2] SMMU v3 CMDQ fix and improvement

[PATCH v2 0/2] SMMU v3 CMDQ fix and improvement

Posted by Jacob Pan 3 months, 2 weeks ago

Hi Will et al,

These two patches are derived from testing SMMU driver with smaller CMDQ
sizes where we see soft lockups.

This happens on HyperV emulated SMMU v3 as well as baremetal ARM servers
with artificially reduced queue size and microbenchmark to stress test
concurrency.

Thanks,

Jacob 

Alexander Grest (1):
  iommu/arm-smmu-v3: Improve CMDQ lock fairness and efficiency

Jacob Pan (1):
  iommu/arm-smmu-v3: Fix CMDQ timeout warning

 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 97 ++++++++++-----------
 1 file changed, 47 insertions(+), 50 deletions(-)

-- 
2.43.0

Re: [PATCH v2 0/2] SMMU v3 CMDQ fix and improvement

Posted by Jacob Pan 3 months, 1 week ago

Hi Will,

Just a gentle reminder, appreciated.

@Nicolin, were you able to evaluate these?

By the way, I incorporated your review comments in v2, except for
extracting the function arm_smmu_cmdq_poll_until_enough_space(),
primarily due to concerns with the IRQ flags.

Thanks,

Jacob

 On Mon, 20 Oct 2025 15:43:51 -0700 Jacob
Pan <jacob.pan@linux.microsoft.com> wrote:

> Hi Will et al,
> 
> These two patches are derived from testing SMMU driver with smaller
> CMDQ sizes where we see soft lockups.
> 
> This happens on HyperV emulated SMMU v3 as well as baremetal ARM
> servers with artificially reduced queue size and microbenchmark to
> stress test concurrency.
> 
> Thanks,
> 
> Jacob 
> 
> Alexander Grest (1):
>   iommu/arm-smmu-v3: Improve CMDQ lock fairness and efficiency
> 
> Jacob Pan (1):
>   iommu/arm-smmu-v3: Fix CMDQ timeout warning
> 
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 97
> ++++++++++----------- 1 file changed, 47 insertions(+), 50
> deletions(-)
>