Ignore:
Timestamp:
Jun 25, 2014, 4:27:33 PM (5 years ago)
Author:
cameron
Message:

Clean-ups

File:
1 edited

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  • docs/Working/re/sse2.tex

    r3893 r3896  
    5151primarily DFA-based with heuristics for important special cases.   
    5252The agrep implementation does not support
    53 some of the common regular expression syntax feature and is limited to
     53some of the common regular expression syntax features and is limited to
    5454patterns of at most 32 characters.   As a backtracking implementation,
    5555pcregrep supports more regular expression features, but is not
     
    6969
    7070\paragraph*{Test Expressions} Each grep implementation was evaluated
    71 against the five regular expressions shown
     71against the six regular expressions shown
    7272in Table \ref{RegularExpressions}. 
    7373@ matches the at-sign character.
     
    103103legend style={at={(0.5,-0.15)},
    104104anchor=north,legend columns=-1},
    105 ymax=42,
     105ymax=44,
    106106ybar,
    107107bar width=7pt,
     
    151151
    152152The results for the Email expression illustrate the relative
    153 advantage of the Parabix method when the expression to be matched
     153advantage of the bitstreams method when the expression to be matched
    154154does not permit character skipping in the NFA- or DFA-based
    155155implementations.   In this example, our implementation outperforms
     
    159159The URI expression illustrates the performance of the
    160160grep programs with additional regular expression complexity.
    161 As expressions get larger, the number of steps required by
    162 the Parabix implementation increases, so the performance
    163 advantage drops to about 4.5X over nrgrep and 19X over gre2p.
     161All three implementations require more time than for the
     162Email expression, with similar but slightly lower performance ratios maintained.
     163In this example, the performance advantage of the bitstreams implementation
     164drops to about 4.5X over nrgrep and 19X over gre2p.
    16416532557 lines are matched by the URI regex.
    165166
     
    169170our implementation uses just 1.6 cycles per byte to find the
    170171130,243 matching lines.    The gre2p program performs
    171 quite poorly here, slower than the Parabix implementation
    172 by about 70X, while nrgrep is about 5.5X slower.
     172quite poorly here, off the chart at 114 cycles per byte.
     173This is lower than the bitstreams implementation
     174by about 70X.   In this example, nrgrep maintains its relative performance
     175to the bitstreams implementation, about 5.5X slower.
    173176
    174177A more complex triply-nested repetition structure is required by
     
    177180performance advantage of the bitstreams implementation over
    178181the nrgrep and gre2p.   Nevertheless a 2X
    179 advantage over nrgrep is maintained.
     182advantage over nrgrep is still observed.
    180183
    181184\begin{figure}
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