[bug report] iommu_dma_unmap_sg() is very slow then running IO from remote numa node

[Ming Lei]

On Mon, Jul 19, 2021 at 05:14:28PM +0100, John Garry wrote:
> On 09/07/2021 15:24, Ming Lei wrote:
> > > associated compromises.
> > Follows the log of 'perf report'
> > 
> > 1) good(run fio from cpus in the nvme's numa node)
> 
> Hi Ming,
> 
> If you're still interested in this issue, as an experiment only you can try
> my rebased patches here:
> 
> https://github.com/hisilicon/kernel-dev/commits/private-topic-smmu-5.14-cmdq-4
> 
> I think that you should see a significant performance boost.

There is build issue, please check your tree:

  MODPOST vmlinux.symvers
  MODINFO modules.builtin.modinfo
  GEN     modules.builtin
  LD      .tmp_vmlinux.btf
ld: Unexpected GOT/PLT entries detected!
ld: Unexpected run-time procedure linkages detected!
ld: drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.o: in function `smmu_test_store':
/root/git/linux/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c:3892: undefined reference to `smmu_test_core'
  BTF     .btf.vmlinux.bin.o
pahole: .tmp_vmlinux.btf: No such file or directory
  LD      .tmp_vmlinux.kallsyms1
.btf.vmlinux.bin.o: file not recognized: file format not recognized
make: *** [Makefile:1177: vmlinux] Error 1


Thanks, 
Ming