Re: [PATCH v2 1/2] perf jevents: add iommu page table walk metrics

[sashiko-bot@kernel.org]

> From: Jacob Lefkowitz <jlefkowi@akamai.com>
> 
> Adds page table walk metrics specfically to perf jevents for AMD
> platforms to enhance observability into IOMMU overhead. The metrics
> are supported on Zen 2 and neweer processors. They are implemented
> using the amd_iommu PMU events.
> 
> The list of metrics added here are:
> - lpm_iommu_ptw_reads_per_tlb_miss
> - lpm_iommu_ptw_nested_read_ratio
> - lpm_iommu_ptw_guest_read_ratio
> - lpm_iommu_trans_per_sec
> 
> The changes here have been tested with 'sleep 10' as the workload:
> 
> perf stat -M iommuptw --per-socket --metric-only -j -a -- sleep 10
> {"socket" : "S0", "counters" : 8,
> "reads/tlb_miss lpm_iommu_ptw_reads_per_tlb_miss" : "0.5",
> "%  lpm_iommu_ptw_nested_read_ratio" : "none",
> "%  lpm_iommu_ptw_guest_read_ratio" : "0.0",
> "trans/s  lpm_iommu_trans_per_sec" : "971.5"}
> {"socket" : "S1", "counters" : 0,
> "reads/tlb_miss  lpm_iommu_ptw_reads_per_tlb_miss" : "none",
> "%  lpm_iommu_ptw_nested_read_ratio" : "none",
> "%  lpm_iommu_ptw_guest_read_ratio" : "none,
> "trans/s  lpm_iommu_trans_per_sec" : "none"}
> 
> Signed-off-by: Jacob Lefkowitz <jlefkowi@akamai.com>

Sashiko has reviewed this patch and found no issues.

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