Comment # 1 on bug 1198972 from Jon Brightwell

#perf top -p pid 4000hz

29.23%  [kernel]      [k] read_extent_buffer                                    
15.74%  [kernel]      [k]
trace_event_type_funcs_svcrdma_encode_read+0x7fffff3a5ebe                       
12.64%  [kernel]      [k] map_private_extent_buffer                             
12.32%  [kernel]      [k] nf_tables_fill_gen_info.isra.55                       
9.48%  [kernel]      [k] print_fmt_xprtrdma_rxprt+0x7fffff3a5ee8                
3.97%  [kernel]      [k] __radix_tree_lookup                                    
2.24%  [kernel]      [k] mark_page_accessed                                     
1.50%  [kernel]      [k] generic_bin_search.constprop.41                        
1.46%  [kernel]      [k] print_fmt_xprtrdma_rdch_event+0x7fffff3a5f0f           
1.33%  [kernel]      [k] rpcrdma_ep_disconnect                                  
1.08%  [kernel]      [k] btrfs_comp_cpu_keys                                    
0.92%  [kernel]      [k] find_extent_buffer                                     
0.76%  [kernel]      [k] nf_tables_getobj                                       
0.76%  [kernel]      [k]
trace_event_type_funcs_svcrdma_wc_receive+0x7fffff3a5eb1                        
0.73%  [kernel]      [k]
trace_event_type_funcs_svcrdma_error_event+0x7fffff3a5ec5                       
0.73%  [kernel]      [k]
trace_event_type_funcs_svcrdma_dma_map_rwctx+0x7fffff3a5eab                     
0.72%  [kernel]      [k] print_fmt_xprtrdma_connect_class+0x7fffff3a5ef2        
0.70%  [kernel]      [k]
trace_event_type_funcs_svcrdma_post_recv+0x7fffff3a5ea8                         
0.60%  [kernel]      [k] read_hpet                                              
0.50%  [kernel]      [k] btrfs_search_slot