A. As Supplied - Cold Boot ************************** $ sudo dmesg | grep IOMMU [ 0.710610] pci 0000:00:00.2: AMD-Vi: Unable to read/write to IOMMU perf counter. [ 0.714365] pci 0000:00:00.2: AMD-Vi: Found IOMMU cap 0x40 [ 0.984616] AMD-Vi: AMD IOMMUv2 driver by Joerg Roedel $ sudo perf list | grep iommu intel_iommu:bounce_map_sg [Tracepoint event] intel_iommu:bounce_map_single [Tracepoint event] intel_iommu:bounce_unmap_single [Tracepoint event] intel_iommu:map_sg [Tracepoint event] intel_iommu:map_single [Tracepoint event] intel_iommu:unmap_sg [Tracepoint event] intel_iommu:unmap_single [Tracepoint event] iommu:add_device_to_group [Tracepoint event] iommu:attach_device_to_domain [Tracepoint event] iommu:detach_device_from_domain [Tracepoint event] iommu:io_page_fault [Tracepoint event] iommu:map [Tracepoint event] iommu:remove_device_from_group [Tracepoint event] iommu:unmap [Tracepoint event] No amd_iommu events listed. B. As Supplied - Warm Boot ************************** $ sudo dmesg | grep IOMMU [ 0.515523] pci 0000:00:00.2: AMD-Vi: IOMMU performance counters supported [ 0.519236] pci 0000:00:00.2: AMD-Vi: Found IOMMU cap 0x40 [ 0.520549] perf/amd_iommu: Detected AMD IOMMU #0 (2 banks, 4 counters/bank). [ 0.795781] AMD-Vi: AMD IOMMUv2 driver by Joerg Roedel $ sudo perf stat -e 'amd_iommu_0/cmd_processed/, amd_iommu_0/cmd_processed_inv/, amd_iommu_0/ign_rd_wr_mmio_1ff8h/, amd_iommu_0/int_dte_hit/, amd_iommu_0/int_dte_mis/, amd_iommu_0/mem_dte_hit/, amd_iommu_0/mem_dte_mis/, amd_iommu_0/mem_iommu_tlb_pde_hit/, amd_iommu_0/mem_iommu_tlb_pde_mis/, amd_iommu_0/mem_iommu_tlb_pte_hit/, amd_iommu_0/mem_iommu_tlb_pte_mis/, amd_iommu_0/mem_pass_excl/, amd_iommu_0/mem_pass_pretrans/, amd_iommu_0/mem_pass_untrans/, amd_iommu_0/mem_target_abort/, amd_iommu_0/mem_trans_total/, amd_iommu_0/page_tbl_read_gst/, amd_iommu_0/page_tbl_read_nst/, amd_iommu_0/page_tbl_read_tot/, amd_iommu_0/smi_blk/, amd_iommu_0/smi_recv/, amd_iommu_0/tlb_inv/, amd_iommu_0/vapic_int_guest/, amd_iommu_0/vapic_int_non_guest/' sleep 10 Performance counter stats for 'system wide': 0 amd_iommu_0/cmd_processed/ (33.39%) 0 amd_iommu_0/cmd_processed_inv/ (33.06%) 0 amd_iommu_0/ign_rd_wr_mmio_1ff8h/ (33.58%) 842,245,888,947,849 amd_iommu_0/int_dte_hit/ (33.42%) 848,982,159,636,118 amd_iommu_0/int_dte_mis/ (33.15%) 835,698,854,752,581 amd_iommu_0/mem_dte_hit/ (33.68%) 839,060,819,932,270 amd_iommu_0/mem_dte_mis/ (33.55%) 0 amd_iommu_0/mem_iommu_tlb_pde_hit/ (33.44%) 837,231,240,047,576 amd_iommu_0/mem_iommu_tlb_pde_mis/ (33.62%) 842,688,371,629,123 amd_iommu_0/mem_iommu_tlb_pte_hit/ (33.40%) 851,647,568,857,291 amd_iommu_0/mem_iommu_tlb_pte_mis/ (33.05%) 0 amd_iommu_0/mem_pass_excl/ (33.30%) 0 amd_iommu_0/mem_pass_pretrans/ (33.36%) 852,801,037,224,491 amd_iommu_0/mem_pass_untrans/ (33.01%) 0 amd_iommu_0/mem_target_abort/ (33.50%) 46,371 amd_iommu_0/mem_trans_total/ (33.28%) 0 amd_iommu_0/page_tbl_read_gst/ (33.00%) 1,663 amd_iommu_0/page_tbl_read_nst/ (33.55%) 17 amd_iommu_0/page_tbl_read_tot/ (33.38%) 0 amd_iommu_0/smi_blk/ (33.28%) 0 amd_iommu_0/smi_recv/ (33.49%) 0 amd_iommu_0/tlb_inv/ (33.32%) 0 amd_iommu_0/vapic_int_guest/ (32.96%) 318 amd_iommu_0/vapic_int_non_guest/ (33.28%) 10.001298695 seconds time elapsed C. Revert + Update ****************** $ sudo dmesg | grep IOMMU [ 0.557917] pci 0000:00:00.2: AMD-Vi: IOMMU performance counters supported [ 0.561705] pci 0000:00:00.2: AMD-Vi: Found IOMMU cap 0x40 [ 0.563004] perf/amd_iommu: Detected AMD IOMMU #0 (2 banks, 4 counters/bank). [ 0.905418] AMD-Vi: AMD IOMMUv2 driver by Joerg Roedel $ sudo perf list | grep iommu amd_iommu_0/cmd_processed/ [Kernel PMU event] amd_iommu_0/cmd_processed_inv/ [Kernel PMU event] amd_iommu_0/ign_rd_wr_mmio_1ff8h/ [Kernel PMU event] amd_iommu_0/int_dte_hit/ [Kernel PMU event] amd_iommu_0/int_dte_mis/ [Kernel PMU event] amd_iommu_0/mem_dte_hit/ [Kernel PMU event] amd_iommu_0/mem_dte_mis/ [Kernel PMU event] amd_iommu_0/mem_iommu_tlb_pde_hit/ [Kernel PMU event] amd_iommu_0/mem_iommu_tlb_pde_mis/ [Kernel PMU event] amd_iommu_0/mem_iommu_tlb_pte_hit/ [Kernel PMU event] amd_iommu_0/mem_iommu_tlb_pte_mis/ [Kernel PMU event] amd_iommu_0/mem_pass_excl/ [Kernel PMU event] amd_iommu_0/mem_pass_pretrans/ [Kernel PMU event] amd_iommu_0/mem_pass_untrans/ [Kernel PMU event] amd_iommu_0/mem_target_abort/ [Kernel PMU event] amd_iommu_0/mem_trans_total/ [Kernel PMU event] amd_iommu_0/page_tbl_read_gst/ [Kernel PMU event] amd_iommu_0/page_tbl_read_nst/ [Kernel PMU event] amd_iommu_0/page_tbl_read_tot/ [Kernel PMU event] amd_iommu_0/smi_blk/ [Kernel PMU event] amd_iommu_0/smi_recv/ [Kernel PMU event] amd_iommu_0/tlb_inv/ [Kernel PMU event] amd_iommu_0/vapic_int_guest/ [Kernel PMU event] amd_iommu_0/vapic_int_non_guest/ [Kernel PMU event] intel_iommu:bounce_map_sg [Tracepoint event] intel_iommu:bounce_map_single [Tracepoint event] intel_iommu:bounce_unmap_single [Tracepoint event] intel_iommu:map_sg [Tracepoint event] intel_iommu:map_single [Tracepoint event] intel_iommu:unmap_sg [Tracepoint event] intel_iommu:unmap_single [Tracepoint event] iommu:add_device_to_group [Tracepoint event] iommu:attach_device_to_domain [Tracepoint event] iommu:detach_device_from_domain [Tracepoint event] iommu:io_page_fault [Tracepoint event] iommu:map [Tracepoint event] iommu:remove_device_from_group [Tracepoint event] iommu:unmap [Tracepoint event] $ sudo perf stat -e 'amd_iommu_0/cmd_processed/, amd_iommu_0/cmd_processed_inv/, amd_iommu_0/ign_rd_wr_mmio_1ff8h/, amd_iommu_0/int_dte_hit/, amd_iommu_0/int_dte_mis/, amd_iommu_0/mem_dte_hit/, amd_iommu_0/mem_dte_mis/, amd_iommu_0/mem_iommu_tlb_pde_hit/, amd_iommu_0/mem_iommu_tlb_pde_mis/, amd_iommu_0/mem_iommu_tlb_pte_hit/, amd_iommu_0/mem_iommu_tlb_pte_mis/, amd_iommu_0/mem_pass_excl/, amd_iommu_0/mem_pass_pretrans/, amd_iommu_0/mem_pass_untrans/, amd_iommu_0/mem_target_abort/, amd_iommu_0/mem_trans_total/, amd_iommu_0/page_tbl_read_gst/, amd_iommu_0/page_tbl_read_nst/, amd_iommu_0/page_tbl_read_tot/, amd_iommu_0/smi_blk/, amd_iommu_0/smi_recv/, amd_iommu_0/tlb_inv/, amd_iommu_0/vapic_int_guest/, amd_iommu_0/vapic_int_non_guest/' sleep 10 Performance counter stats for 'system wide': 36 amd_iommu_0/cmd_processed/ (33.30%) 20 amd_iommu_0/cmd_processed_inv/ (33.34%) 0 amd_iommu_0/ign_rd_wr_mmio_1ff8h/ (33.38%) 842,158,150,822,877 amd_iommu_0/int_dte_hit/ (33.42%) 0 amd_iommu_0/int_dte_mis/ (33.44%) 310 amd_iommu_0/mem_dte_hit/ (33.44%) 841,709,432,950,259 amd_iommu_0/mem_dte_mis/ (33.44%) 0 amd_iommu_0/mem_iommu_tlb_pde_hit/ (33.44%) 320 amd_iommu_0/mem_iommu_tlb_pde_mis/ (33.42%) 182 amd_iommu_0/mem_iommu_tlb_pte_hit/ (33.38%) 10,863 amd_iommu_0/mem_iommu_tlb_pte_mis/ (33.34%) 0 amd_iommu_0/mem_pass_excl/ (33.30%) 0 amd_iommu_0/mem_pass_pretrans/ (33.28%) 10,834 amd_iommu_0/mem_pass_untrans/ (33.28%) 0 amd_iommu_0/mem_target_abort/ (33.28%) 1,430 amd_iommu_0/mem_trans_total/ (33.28%) 0 amd_iommu_0/page_tbl_read_gst/ (33.28%) 201 amd_iommu_0/page_tbl_read_nst/ (33.28%) 192 amd_iommu_0/page_tbl_read_tot/ (33.28%) 0 amd_iommu_0/smi_blk/ (33.28%) 0 amd_iommu_0/smi_recv/ (33.28%) 0 amd_iommu_0/tlb_inv/ (33.28%) 0 amd_iommu_0/vapic_int_guest/ (33.28%) 336 amd_iommu_0/vapic_int_non_guest/ (33.28%) 10.001183400 seconds time elapsed