📄 ch39_04.htm
字号:
<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 39] 39.4 Average Command Runtimes with runtime </TITLE><METANAME="DC.title"CONTENT="UNIX Power Tools"><METANAME="DC.creator"CONTENT="Jerry Peek, Tim O'Reilly & Mike Loukides"><METANAME="DC.publisher"CONTENT="O'Reilly & Associates, Inc."><METANAME="DC.date"CONTENT="1998-08-04T21:50:13Z"><METANAME="DC.type"CONTENT="Text.Monograph"><METANAME="DC.format"CONTENT="text/html"SCHEME="MIME"><METANAME="DC.source"CONTENT="1-56592-260-3"SCHEME="ISBN"><METANAME="DC.language"CONTENT="en-US"><METANAME="generator"CONTENT="Jade 1.1/O'Reilly DocBook 3.0 to HTML 4.0"><LINKREV="made"HREF="mailto:online-books@oreilly.com"TITLE="Online Books Comments"><LINKREL="up"HREF="ch39_01.htm"TITLE="39. Time and Performance"><LINKREL="prev"HREF="ch39_03.htm"TITLE="39.3 The csh time variable "><LINKREL="next"HREF="ch39_05.htm"TITLE="39.5 Why Is the System So Slow? "></HEAD><BODYBGCOLOR="#FFFFFF"TEXT="#000000"><DIVCLASS="htmlnav"><H1><IMGSRC="gifs/smbanner.gif"ALT="UNIX Power Tools"USEMAP="#srchmap"BORDER="0"></H1><MAPNAME="srchmap"><AREASHAPE="RECT"COORDS="0,0,466,58"HREF="index.htm"ALT="UNIX Power Tools"><AREASHAPE="RECT"COORDS="467,0,514,18"HREF="jobjects/fsearch.htm"ALT="Search this book"></MAP><TABLEWIDTH="515"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch39_03.htm"TITLE="39.3 The csh time variable "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 39.3 The csh time variable "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 39<BR>Time and Performance</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch39_05.htm"TITLE="39.5 Why Is the System So Slow? "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 39.5 Why Is the System So Slow? "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-4560">39.4 Average Command Runtimes with runtime </A></H2><TABLECLASS="para.programreference"BORDER="1"><TR><THVALIGN="TOP"><ACLASS="programreference"HREF="examples/index.htm"TITLE="runtime">runtime</A><BR></TH><TDVALIGN="TOP"><ACLASS="indexterm"NAME="AUTOID-43730"></A><ACLASS="indexterm"NAME="AUTOID-43732"></A><ACLASS="indexterm"NAME="AUTOID-43735"></A><ACLASS="indexterm"NAME="AUTOID-43737"></A>The<SPANCLASS="link"><EMCLASS="emphasis">time</EM> command (<ACLASS="linkend"HREF="ch39_02.htm"TITLE="Timing Programs ">39.2</A>)</SPAN>will time a single run of a command - but the results can vary from runto run.The <EMCLASS="emphasis">runtime</EM> script runs a command the number of times you specify,then averages the results.For example:</TD></TR></TABLE><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>runtime -5 getdata 0.5 outfile</B></CODE> <ICLASS="lineannotation">...wait a while...</I>runtime summary - 5 runs of % getdata 0.5 outfile(working directory = /users/jerry/.src/getdata)First run started at: Thu Mar 19 09:33:58 EST 1992Last run finished at: Thu Mar 19 09:36:41 EST 1992------------------------ RUN # ***INDIVIDUAL RESULTS*** 1 1.0u 7.4s 1:06 12% 0+108k 0+0io 0pf+0w 2 0.2u 0.8s 0:05 16% 0+128k 0+0io 0pf+0w 3 0.2u 1.3s 0:11 13% 0+116k 0+0io 0pf+0w 4 0.4u 2.7s 0:25 12% 0+108k 0+0io 0pf+0w 5 0.9u 5.9s 0:53 12% 0+108k 0+0io 0pf+0wAVERAGES: 0.54u 3.62s 0:32 0+113k 0+0io 0pf+0w </PRE></BLOCKQUOTE></P><PCLASS="para">It's good for testing different versions of a program to find thefastest (or slowest!).If you're writing a program that will run a lot, shaving 10% or 20% offits time can be worth the work.</P><PCLASS="para">Note that the command you run can't have any redirection in it; that'sbecause <EMCLASS="emphasis">runtime</EM> does some redirection of its own.You can redirect the output of runtime into a log file though, and runthe whole mess in the background. For example:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>runtime -5 getdata 0.5 outfile > runtime.out &</B></CODE>[1] 12233</PRE></BLOCKQUOTE></P><PCLASS="para">The summary will go to the <EMCLASS="emphasis">runtime.out</EM> file.</P><DIVCLASS="sect1info"><PCLASS="SECT1INFO">- <SPANCLASS="authorinitials">JP</SPAN></P></DIV></DIV><DIVCLASS="htmlnav"><P></P><HRALIGN="LEFT"WIDTH="515"TITLE="footer"><TABLEWIDTH="515"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch39_03.htm"TITLE="39.3 The csh time variable "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 39.3 The csh time variable "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><ACLASS="book"HREF="index.htm"TITLE="UNIX Power Tools"><IMGSRC="gifs/txthome.gif"SRC="gifs/txthome.gif"ALT="UNIX Power Tools"BORDER="0"></A></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch39_05.htm"TITLE="39.5 Why Is the System So Slow? "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 39.5 Why Is the System So Slow? "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">39.3 The csh time variable </TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><ACLASS="index"HREF="index/idx_0.htm"TITLE="Book Index"><IMGSRC="gifs/index.gif"SRC="gifs/index.gif"ALT="Book Index"BORDER="0"></A></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172">39.5 Why Is the System So Slow? </TD></TR></TABLE><HRALIGN="LEFT"WIDTH="515"TITLE="footer"><IMGSRC="gifs/smnavbar.gif"SRC="gifs/smnavbar.gif"USEMAP="#map"BORDER="0"ALT="The UNIX CD Bookshelf Navigation"><MAPNAME="map"><AREASHAPE="RECT"COORDS="0,0,73,21"HREF="../index.htm"ALT="The UNIX CD Bookshelf"><AREASHAPE="RECT"COORDS="74,0,163,21"HREF="index.htm"ALT="UNIX Power Tools"><AREASHAPE="RECT"COORDS="164,0,257,21"HREF="../unixnut/index.htm"ALT="UNIX in a Nutshell"><AREASHAPE="RECT"COORDS="258,0,321,21"HREF="../vi/index.htm"ALT="Learning the vi Editor"><AREASHAPE="RECT"COORDS="322,0,378,21"HREF="../sedawk/index.htm"ALT="sed & awk"><AREASHAPE="RECT"COORDS="379,0,438,21"HREF="../ksh/index.htm"ALT="Learning the Korn Shell"><AREASHAPE="RECT"COORDS="439,0,514,21"HREF="../lrnunix/index.htm"ALT="Learning the UNIX Operating System"></MAP></DIV></BODY></HTML>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -