\documentclass{standalone}

\usepackage[T1]{fontenc}
\usepackage[default]{opensans}
\usepackage[scaled]{beramono}

\usepackage{tikz}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}
\usepgfplotslibrary{statistics}

\begin{document}
	\begin{tikzpicture}
		\begin{axis}[
				ylabel={write [GB/s]},
				xlabel={\# Ranks},
				x label style={font=\footnotesize, yshift=2mm},
				y label style={font=\footnotesize},
				tick label style={/pgf/number format/assume math mode=true},
				title={Benchmark Data},
				title style={yshift=-3mm},
				legend style={font=\footnotesize, legend columns=-1, column sep=1ex},
				legend pos=south east,
				legend entries={upstream,,{no transformation},},
				reverse legend,
				ymin=0,ymax=14,
				xmin=0,xmax=41,
				width=90mm,height=45mm
			]
			\addplot[thick, color=red, domain=1:40] {5.042768 + 0.258673 * min(x, 31.536102)};
			\addplot[color=red,only marks,mark=*,mark size=0.9,opacity=.05]
				table[x=n_ranks, y=value] {orig-NMC-transfer-writeThroughputGBps.txt};
			\addplot[thick, color=blue, domain=1:40] {5.049962 + 0.308594 * min(x, 25.657012)};
			\addplot[color=blue,only marks,mark=*,mark size=0.9,opacity=.05]
				table[x=n_ranks, y=value] {notransform-NMC-transfer-writeThroughputGBps.txt};
		\end{axis}
	\end{tikzpicture}
\end{document}