An OpenMP implementation of the n-queens problem. This is also the description of “m-queens” so we can see how they compare. This runs 4x as quick, though the board sizes may be different. This shows processes on each core.
Topdown profile shows a surprisingly high branch mispredict rate. Otherwise frontend stalls and retirement rate are similar.
AMD metrics show many floating point instructions and very little L2 access.
elapsed 59.706
on_cpu 0.734 # 11.75 / 16 cores
utime 700.580
stime 0.941
nvcsw 1969 # 20.79%
nivcsw 7502 # 79.21%
inblock 0 # 0.00/sec
onblock 12560 # 210.36/sec
cpu-clock 701577930989 # 701.578 seconds
task-clock 701582852603 # 701.583 seconds
page faults 147260 # 209.897/sec
context switches 9598 # 13.680/sec
cpu migrations 266 # 0.379/sec
major page faults 2 # 0.003/sec
minor page faults 147258 # 209.894/sec
alignment faults 0 # 0.000/sec
emulation faults 0 # 0.000/sec
branches 358274822489 # 105.547 branches per 1000 inst
branch misses 53094091069 # 14.82% branch miss
conditional 268491549572 # 79.097 conditional branches per 1000 inst
indirect 47097724 # 0.014 indirect branches per 1000 inst
cpu-cycles 2910026096341 # 3.02 GHz
instructions 3393651570228 # 1.17 IPC
slots 5826052535754 #
retiring 1150107894282 # 19.7% (30.4%)
-- ucode 16366252 # 0.0%
-- fastpath 1150091528030 # 19.7%
frontend 1205152582022 # 20.7% (31.8%)
-- latency 1044472772652 # 17.9%
-- bandwidth 160679809370 # 2.8%
backend 855912736625 # 14.7% (22.6%)
-- cpu 295050537557 # 5.1%
-- memory 560862199068 # 9.6%
speculation 577782310149 # 9.9% (15.2%) high
-- branch mispredict 577772539962 # 9.9%
-- pipeline restart 9770187 # 0.0%
smt-contention 2037084896785 # 35.0% ( 0.0%)
cpu-cycles 2907871863146 # 3.04 GHz
instructions 3390883633345 # 1.17 IPC
instructions 1133281902047 # 0.121 l2 access per 1000 inst
l2 hit from l1 119341967 # 14.89% l2 miss
l2 miss from l1 11697818 #
l2 hit from l2 pf 8853005 #
l3 hit from l2 pf 4524968 #
l3 miss from l2 pf 4161961 #
instructions 1130949836740 # 209.890 float per 1000 inst
float 512 67 # 0.000 AVX-512 per 1000 inst
float 256 656 # 0.000 AVX-256 per 1000 inst
float 128 237375367252 # 209.890 AVX-128 per 1000 inst
float MMX 0 # 0.000 MMX per 1000 inst
float scalar 0 # 0.000 scalar per 1000 inst
Intel metrics
elapsed 205.379
on_cpu 0.810 # 12.96 / 16 cores
utime 2660.432
stime 0.462
nvcsw 1992 # 8.22%
nivcsw 22250 # 91.78%
inblock 8 # 0.04/sec
onblock 1456 # 7.09/sec
cpu-clock 2661041175202 # 2661.041 seconds
task-clock 2661049045772 # 2661.049 seconds
page faults 140831 # 52.923/sec
context switches 25082 # 9.426/sec
cpu migrations 258 # 0.097/sec
major page faults 0 # 0.000/sec
minor page faults 140831 # 52.923/sec
alignment faults 0 # 0.000/sec
emulation faults 0 # 0.000/sec
branches 803581484498 # 81.202 branches per 1000 inst
branch misses 164085751671 # 20.42% branch miss
conditional 803581501170 # 81.202 conditional branches per 1000 inst
indirect 209212950465 # 21.141 indirect branches per 1000 inst
slots 4783298033636 #
retiring 1671294828132 # 34.9% (34.9%)
-- ucode 94088025026 # 2.0%
-- fastpath 1577206803106 # 33.0%
frontend 560253074951 # 11.7% (11.7%)
-- latency 413909373463 # 8.7%
-- bandwidth 146343701488 # 3.1%
backend 344172623109 # 7.2% ( 7.2%) low
-- cpu 290550559133 # 6.1%
-- memory 53622063976 # 1.1%
speculation 2234265584235 # 46.7% (46.7%) high
-- branch mispredict 2234120655291 # 46.7%
-- pipeline restart 144928944 # 0.0%
smt-contention 0 # 0.0% ( 0.0%)
cpu-cycles 1725231955347 # 1.53 GHz
instructions 1873420941187 # 1.09 IPC
l2 access 271608413 # 0.157 l2 access per 1000 inst
l2 miss 82913103 # 30.53% l2 miss
Process overview
399 processes
48 qn24b_openmp 11241.12 0.16
68 clinfo 16.52 5.99
38 vulkaninfo 1.13 1.15
4 vulkani:disk$0 0.12 0.12
6 glxinfo:gdrv0 0.08 0.09
6 glxinfo:gl0 0.08 0.09
6 php 0.06 0.07
2 llvmpipe-0 0.06 0.06
2 llvmpipe-1 0.06 0.06
2 llvmpipe-10 0.06 0.06
2 llvmpipe-11 0.06 0.06
2 llvmpipe-12 0.06 0.06
2 llvmpipe-13 0.06 0.06
2 llvmpipe-14 0.06 0.06
2 llvmpipe-15 0.06 0.06
2 llvmpipe-2 0.06 0.06
2 llvmpipe-3 0.06 0.06
2 llvmpipe-4 0.06 0.06
2 llvmpipe-5 0.06 0.06
2 llvmpipe-6 0.06 0.06
2 llvmpipe-7 0.06 0.06
2 llvmpipe-8 0.06 0.06
2 llvmpipe-9 0.06 0.06
2 glxinfo 0.05 0.04
6 clang 0.04 0.08
2 glxinfo:cs0 0.04 0.03
2 glxinfo:disk$0 0.04 0.03
2 glxinfo:sh0 0.04 0.03
2 glxinfo:shlo0 0.04 0.03
3 rocminfo 0.03 0.00
1 lspci 0.00 0.03
1 ps 0.00 0.01
82 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
4 gmain 0.00 0.00
3 n-queens 0.00 0.00
2 cc 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 dconf worker 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
47 maximum processes
Computation blocks
112879) n-queens cpu=4 start=5.65 finish=20.31
112880) qn24b_openmp cpu=12 start=5.65 finish=20.31
112881) qn24b_openmp cpu=8 start=5.65 finish=20.31
112882) qn24b_openmp cpu=15 start=5.65 finish=20.31
112883) qn24b_openmp cpu=10 start=5.65 finish=20.31
112884) qn24b_openmp cpu=1 start=5.65 finish=20.31
112885) qn24b_openmp cpu=3 start=5.65 finish=20.31
112886) qn24b_openmp cpu=5 start=5.65 finish=20.31
112887) qn24b_openmp cpu=4 start=5.66 finish=20.31
112888) qn24b_openmp cpu=6 start=5.66 finish=20.31
112889) qn24b_openmp cpu=13 start=5.66 finish=20.31
112890) qn24b_openmp cpu=0 start=5.66 finish=20.31
112891) qn24b_openmp cpu=2 start=5.66 finish=20.31
112892) qn24b_openmp cpu=9 start=5.66 finish=20.31
112893) qn24b_openmp cpu=7 start=5.66 finish=20.31
112894) qn24b_openmp cpu=11 start=5.66 finish=20.31
112895) qn24b_openmp cpu=14 start=5.66 finish=20.31