x86 trap-in cost

           bash-953   [002] .N..   226.508433: loop_test: virt-test hvc	258	1048576	min:	224	max:	24397
            bash-953   [001] .N..   228.047424: hvc_test: [4949755] before: 370039fc92, after: 37003cebfe, diff: 2ef6c
            bash-953   [001] .N..   230.766585: loop_test: virt-test hvc	257	1048576	min:	224	max:	192364
            bash-953   [003] .N..   234.547525: hvc_test: [8026078] before: 3a2dd7208e, after: 3a2dda016f, diff: 2e0e1
            bash-953   [003] .N..   235.047505: hvc_test: [8273842] before: 3a6c6d1062, after: 3a6c6feba7, diff: 2db45
            bash-953   [003] .N..   235.276287: loop_test: virt-test hvc	257	1048576	min:	224	max:	188641
            bash-953   [003] .N..   239.495283: loop_test: virt-test hvc	258	1048576	min:	224	max:	33216
            bash-953   [003] .N..   243.755548: loop_test: virt-test hvc	260	1048576	min:	224	max:	32484
            bash-953   [003] .N..   248.012592: loop_test: virt-test hvc	259	1048576	min:	224	max:	29870
            bash-953   [003] .N..   252.271046: loop_test: virt-test hvc	259	1048576	min:	224	max:	30129
            bash-953   [003] .N..   256.519251: loop_test: virt-test hvc	260	1048576	min:	224	max:	33907
            bash-953   [003] .N..   260.760079: loop_test: virt-test hvc	258	1048576	min:	224	max:	35022
            bash-953   [003] .N..   262.547882: hvc_test: [21851353] before: 47dea3630d, after: 47dea640c6, diff: 2ddb9
            bash-953   [003] .N..   265.013155: loop_test: virt-test hvc	259	1048576	min:	224	max:	187833
            bash-953   [003] .N..   268.047927: hvc_test: [24557332] before: 4a8f14a48c, after: 4a8f174864, diff: 2a3d8
            bash-953   [003] .N..   269.278541: loop_test: virt-test hvc	258	1048576	min:	224	max:	173016
            bash-953   [003] .N..   273.535526: loop_test: virt-test hvc	260	1048576	min:	224	max:	30648
            bash-953   [003] .N..   277.776993: loop_test: virt-test hvc	259	1048576	min:	224	max:	27690
            bash-953   [003] .N..   280.048087: hvc_test: [30477870] before: 506d23029b, after: 506d25d881, diff: 2d5e6
            bash-953   [003] .N..   282.046576: loop_test: virt-test hvc	261	1048576	min:	224	max:	185830
            bash-953   [003] .N..   286.292830: loop_test: virt-test hvc	260	1048576	min:	224	max:	33834
            bash-953   [003] .N..   290.534851: loop_test: virt-test hvc	259	1048576	min:	224	max:	34710
            bash-953   [003] .N..   291.048232: hvc_test: [35904745] before: 55ce058164, after: 55ce086cb6, diff: 2eb52
            bash-953   [003] .N..   294.772548: loop_test: virt-test hvc	258	1048576	min:	224	max:	191314
            bash-953   [003] .N..   299.003270: loop_test: virt-test hvc	258	1048576	min:	224	max:	34734
            bash-953   [003] .N..   303.244679: loop_test: virt-test hvc	259	1048576	min:	224	max:	33201
            bash-953   [003] .N..   307.048437: hvc_test: [43821198] before: 5da0c34b21, after: 5da0c636c6, diff: 2eba5