On 27 Oct 2019, at 17:59, Alexey Dokuchaev <da...@freebsd.org> wrote: > > On Sat, Oct 26, 2019 at 04:34:14PM +0200, Dimitry Andric wrote: ... >> I only tested -j24 on a 32-core system, but I could probably repeat the >> experiment with lower and higher -j values: [...] >> >> So ~2.3% difference in real time, which is not too bad I think. > > Well, I'd say it's acceptable. :-/
I also tested at low (-j4) and high (-j32) levels. It turns out that at low -j levels, the difference is less pronounced, just ~1.1% in real time. And at high -j levels, it is more pronounced, ~4.3% in real time. Note also that at high -j levels, the difference in system time seems to get more influence, e.g. at low -j the difference is ~4.5%, while at high -j the difference is ~7.2%. I guess it is because dynamic linking uses more syscalls. At -j4: Results for real time: --------------------------------------------------------------------------- x j4-static-real.txt + j4-dynamic-real.txt N Min Max Median Avg Stddev x 7 5508.58 5548.05 5533.25 5530.2829 12.323855 + 7 5514.68 5660.1 5591.25 5593.5143 59.98042 Difference at 95.0% confidence 63.2314 +/- 50.4309 1.14337% +/- 0.912329% (Student's t, pooled s = 43.2985) Results for user time: --------------------------------------------------------------------------- x j4-static-user.txt + j4-dynamic-user.txt N Min Max Median Avg Stddev x 7 19525.34 19607.74 19593.1 19582.78 29.037717 + 7 20178.84 20348.11 20214.28 20235.057 57.31409 Difference at 95.0% confidence 652.277 +/- 52.9155 3.33087% +/- 0.272077% (Student's t, pooled s = 45.4318) Results for system time: --------------------------------------------------------------------------- x j4-static-sys.txt + j4-dynamic-sys.txt N Min Max Median Avg Stddev x 7 1622.63 1634.98 1629.87 1629.1229 4.7234017 + 7 1672.25 1722.23 1704.49 1703.1729 15.724862 Difference at 95.0% confidence 74.05 +/- 13.5224 4.54539% +/- 0.833228% (Student's t, pooled s = 11.6099) At -j32: Results for real time: --------------------------------------------------------------------------- x j32-static-real.txt + j32-dynamic-real.txt N Min Max Median Avg Stddev x 7 1689.19 1735.36 1707.32 1707.8471 16.500078 + 7 1754.98 1812.57 1777.96 1781.6329 19.554159 Difference at 95.0% confidence 73.7857 +/- 21.0718 4.32039% +/- 1.25627% (Student's t, pooled s = 18.0917) Results for user time: --------------------------------------------------------------------------- x j32-static-user.txt + j32-dynamic-user.txt N Min Max Median Avg Stddev x 7 38545.36 38802.6 38609.87 38641.009 105.11904 + 7 39430.93 39924.98 39856.91 39769.979 185.3612 Difference at 95.0% confidence 1128.97 +/- 175.5 2.92169% +/- 0.457446% (Student's t, pooled s = 150.68) Results for system time: --------------------------------------------------------------------------- x j32-static-sys.txt + j32-dynamic-sys.txt N Min Max Median Avg Stddev x 7 2752.81 2809.97 2781.46 2781.4986 21.86523 + 7 2906.22 3151.93 2932.59 2981.5757 103.79842 Difference at 95.0% confidence 200.077 +/- 87.3629 7.19314% +/- 3.15079% (Student's t, pooled s = 75.0073) -Dimitry
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