A Linux kernel scheduler benchmark. There are nine workloads measuring latency with increasing numbers of threads. Plot below reflects both increased runable threads and usage.
Topdown profile shows mostly memory bound with some frontend stalls.
AMD metrics show backend stalls. There is little floating point code and little L2 access.
elapsed 1556.050
on_cpu 0.645 # 10.32 / 16 cores
utime 16042.943
stime 11.160
nvcsw 1661935 # 45.05%
nivcsw 2026894 # 54.95%
inblock 0 # 0.00/sec
onblock 14568 # 9.36/sec
cpu-clock 16053848559152 # 16053.849 seconds
task-clock 16054114142431 # 16054.114 seconds
page faults 242257 # 15.090/sec
context switches 3696293 # 230.240/sec
cpu migrations 790049 # 49.212/sec
major page faults 57 # 0.004/sec
minor page faults 242200 # 15.086/sec
alignment faults 0 # 0.000/sec
emulation faults 0 # 0.000/sec
branches 8363015807661 # 181.011 branches per 1000 inst
branch misses 1751506043 # 0.02% branch miss
conditional 6129106510907 # 132.659 conditional branches per 1000 inst
indirect 555221078517 # 12.017 indirect branches per 1000 inst
cpu-cycles 73140054874996 # 2.54 GHz
instructions 46237826856780 # 0.63 IPC low
slots 146432173835976 #
retiring 24129100695098 # 16.5% (24.2%)
-- ucode 370520955370 # 0.3%
-- fastpath 23758579739728 # 16.2%
frontend 29102512339367 # 19.9% (29.2%)
-- latency 24587855340780 # 16.8%
-- bandwidth 4514656998587 # 3.1%
backend 46483315674898 # 31.7% (46.6%)
-- cpu 10093079433097 # 6.9%
-- memory 36390236241801 # 24.9%
speculation 2955527432 # 0.0% ( 0.0%) low
-- branch mispredict 2946103259 # 0.0%
-- pipeline restart 9424173 # 0.0%
smt-contention 46714117571170 # 31.9% ( 0.0%)
cpu-cycles 67822818429201 # 2.35 GHz
instructions 43003680601254 # 0.63 IPC low
instructions 14340971853956 # 0.122 l2 access per 1000 inst
l2 hit from l1 1599372168 # 15.28% l2 miss
l2 miss from l1 197105566 #
l2 hit from l2 pf 77075632 #
l3 hit from l2 pf 55117623 #
l3 miss from l2 pf 14657946 #
instructions 14335290807670 # 4.475 float per 1000 inst
float 512 108 # 0.000 AVX-512 per 1000 inst
float 256 480 # 0.000 AVX-256 per 1000 inst
float 128 64152822075 # 4.475 AVX-128 per 1000 inst
float MMX 0 # 0.000 MMX per 1000 inst
float scalar 0 # 0.000 scalar per 1000 inst
instructions 26647384037721 #
opcache 3861767750251 # 144.921 opcache per 1000 inst
opcache miss 7442788516 # 0.2% opcache miss rate
l1 dTLB miss 139727119 # 0.005 L1 dTLB per 1000 inst
l2 dTLB miss 18498881 # 0.001 L2 dTLB per 1000 inst
instructions 52883862220061 #
icache 25470270754 # 0.482 icache per 1000 inst
icache miss 3143824182 # 12.3% icache miss rate
l1 iTLB miss 9913687 # 0.000 L1 iTLB per 1000 inst
l2 iTLB miss 0 # 0.000 L2 iTLB per 1000 inst
tlb flush 146204 # 0.000 TLB flush per 1000 inst
Intel metrics show backend stalls as more CPU-based
elapsed 2139.355
on_cpu 0.565 # 9.04 / 16 cores
utime 19329.698
stime 10.853
nvcsw 1642438 # 46.31%
nivcsw 1904138 # 53.69%
inblock 288 # 0.13/sec
onblock 3760 # 1.76/sec
cpu-clock 19342627391967 # 19342.627 seconds
task-clock 19343100659394 # 19343.101 seconds
page faults 180818 # 9.348/sec
context switches 3556927 # 183.886/sec
cpu migrations 785457 # 40.607/sec
major page faults 66 # 0.003/sec
minor page faults 180752 # 9.345/sec
alignment faults 0 # 0.000/sec
emulation faults 0 # 0.000/sec
branches 4562313428524 # 180.964 branches per 1000 inst
branch misses 259291716 # 0.01% branch miss
conditional 4562313732684 # 180.964 conditional branches per 1000 inst
indirect 1397283320799 # 55.423 indirect branches per 1000 inst
slots 89163987381800 #
retiring 12228322389427 # 13.7% (13.7%) low
-- ucode 4221981936017 # 4.7%
-- fastpath 8006340453410 # 9.0%
frontend 6991394912521 # 7.8% ( 7.8%)
-- latency 5126137258625 # 5.7%
-- bandwidth 1865257653896 # 2.1%
backend 69975878002186 # 78.5% (78.5%) high
-- cpu 67849553454305 # 76.1%
-- memory 2126324547881 # 2.4%
speculation 2900478872 # 0.0% ( 0.0%) low
-- branch mispredict 2772785413 # 0.0%
-- pipeline restart 127693459 # 0.0%
smt-contention 0 # 0.0% ( 0.0%)
cpu-cycles 61862121549034 # 1.75 GHz
instructions 20391443056364 # 0.33 IPC low
l2 access 2429707648 # 0.224 l2 access per 1000 inst
l2 miss 786985989 # 32.39% l2 miss
cpu-cycles 23582529091664 # 3.7% memory latency
load stalls 864295341452 # 3.6% l1 bound
l1 miss 9987194866 # 0.0% l2 bound
l2 miss 6326008394 # 0.0% l3 bound
l3 miss 926737004 # 0.0% dram bound
store_stalls 276316533 # 0.0% store bound
Process summary
8083 processes
7664 schbench 3752749.00 1085.68
68 clinfo 16.21 5.99
38 vulkaninfo 1.52 0.96
4 vulkani:disk$0 0.16 0.10
6 php 0.14 0.23
6 glxinfo:gdrv0 0.11 0.05
6 glxinfo:gl0 0.11 0.05
2 llvmpipe-0 0.08 0.05
2 llvmpipe-1 0.08 0.05
2 llvmpipe-10 0.08 0.05
2 llvmpipe-11 0.08 0.05
2 llvmpipe-12 0.08 0.05
2 llvmpipe-13 0.08 0.05
2 llvmpipe-14 0.08 0.05
2 llvmpipe-15 0.08 0.05
2 llvmpipe-2 0.08 0.05
2 llvmpipe-3 0.08 0.05
2 llvmpipe-4 0.08 0.05
2 llvmpipe-5 0.08 0.05
2 llvmpipe-6 0.08 0.05
2 llvmpipe-7 0.08 0.05
2 llvmpipe-8 0.08 0.05
2 llvmpipe-9 0.08 0.05
6 clang 0.06 0.04
2 glxinfo 0.05 0.03
2 glxinfo:cs0 0.05 0.03
2 glxinfo:disk$0 0.05 0.03
2 glxinfo:sh0 0.05 0.03
2 glxinfo:shlo0 0.05 0.03
3 rocminfo 0.03 0.00
1 lspci 0.00 0.02
1 ps 0.00 0.01
98 sh 0.00 0.00
13 gcc 0.00 0.00
11 gsettings 0.00 0.00
8 stat 0.00 0.00
8 systemd-detect- 0.00 0.00
6 llvm-link 0.00 0.00
5 phoronix-test-s 0.00 0.00
3 gmain 0.00 0.00
2 cc 0.00 0.00
2 dconf worker 0.00 0.00
2 lscpu 0.00 0.00
2 uname 0.00 0.00
2 which 0.00 0.00
2 xset 0.00 0.00
1 date 0.00 0.00
1 dirname 0.00 0.00
1 dmesg 0.00 0.00
1 dmidecode 0.00 0.00
1 grep 0.00 0.00
1 ifconfig 0.00 0.00
1 ip 0.00 0.00
1 lsmod 0.00 0.00
1 mktemp 0.00 0.00
1 qdbus 0.00 0.00
1 readlink 0.00 0.00
1 realpath 0.00 0.00
1 sed 0.00 0.00
1 sort 0.00 0.00
1 stty 0.00 0.00
1 systemctl 0.00 0.00
1 template.sh 0.00 0.00
1 wc 0.00 0.00
1 xrandr 0.00 0.00
0 processes running
1291 maximum processes
Computation structures
87468) schbench cpu=6 start=148.37 finish=178.43
87469) schbench cpu=7 start=148.37 finish=178.43
87470) schbench cpu=2 start=148.37 finish=178.43
87472) schbench cpu=10 start=148.37 finish=178.43
87474) schbench cpu=12 start=148.37 finish=178.43
87476) schbench cpu=15 start=148.37 finish=178.43
87477) schbench cpu=6 start=148.37 finish=178.43
87471) schbench cpu=1 start=148.37 finish=178.43
87473) schbench cpu=4 start=148.37 finish=178.43
87475) schbench cpu=5 start=148.37 finish=178.43
87478) schbench cpu=11 start=148.37 finish=178.43
87479) schbench cpu=9 start=148.37 finish=178.43