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Posted to dev@lucene.apache.org by "Michael McCandless (JIRA)" <ji...@apache.org> on 2013/01/09 13:50:13 UTC

[jira] [Commented] (LUCENE-3178) Native MMapDir

    [ https://issues.apache.org/jira/browse/LUCENE-3178?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13548466#comment-13548466 ] 

Michael McCandless commented on LUCENE-3178:
--------------------------------------------

I haven't looked closely at the patch, but I ran an initial perf test:
{noformat}
                    Task    QPS base      StdDev    QPS comp      StdDev                Pct diff
              AndHighLow     1024.41      (3.1%)      856.52      (2.0%)  -16.4% ( -20% -  -11%)
               LowPhrase       69.04      (1.7%)       58.90      (0.9%)  -14.7% ( -16% -  -12%)
              AndHighMed      193.16      (1.0%)      169.24      (1.4%)  -12.4% ( -14% -  -10%)
                 Respell       55.65      (3.0%)       50.01      (3.3%)  -10.1% ( -15% -   -3%)
                  Fuzzy2       67.18      (3.3%)       60.52      (3.6%)   -9.9% ( -16% -   -3%)
                  Fuzzy1       68.83      (3.4%)       62.65      (3.4%)   -9.0% ( -15% -   -2%)
         LowSloppyPhrase       85.35      (1.8%)       78.64      (1.6%)   -7.9% ( -11% -   -4%)
             LowSpanNear       38.05      (2.9%)       35.14      (3.1%)   -7.6% ( -13% -   -1%)
                Wildcard       99.78      (3.0%)       93.39      (2.9%)   -6.4% ( -12% -    0%)
             MedSpanNear       77.91      (2.2%)       74.26      (2.3%)   -4.7% (  -9% -    0%)
            HighSpanNear        9.24      (2.7%)        8.86      (2.5%)   -4.1% (  -9% -    1%)
        HighSloppyPhrase        2.25      (4.0%)        2.16      (3.8%)   -4.0% ( -11% -    3%)
         MedSloppyPhrase       78.44      (2.2%)       75.35      (2.4%)   -3.9% (  -8% -    0%)
              HighPhrase       30.39      (8.1%)       29.27      (7.9%)   -3.7% ( -18% -   13%)
                 LowTerm      808.93      (5.0%)      779.29      (5.4%)   -3.7% ( -13% -    7%)
               MedPhrase      176.20      (5.9%)      169.98      (5.5%)   -3.5% ( -14% -    8%)
                 Prefix3       51.16      (6.0%)       49.53      (4.9%)   -3.2% ( -13% -    8%)
             AndHighHigh       69.32      (2.3%)       67.21      (2.4%)   -3.0% (  -7% -    1%)
                  IntNRQ       10.99     (10.0%)       10.86      (9.0%)   -1.2% ( -18% -   19%)
                 MedTerm      329.36     (10.0%)      325.83     (11.9%)   -1.1% ( -20% -   23%)
               OrHighMed       67.18      (2.2%)       66.64      (4.5%)   -0.8% (  -7% -    6%)
              OrHighHigh       42.91      (2.5%)       42.59      (4.8%)   -0.7% (  -7% -    6%)
               OrHighLow       62.96      (2.3%)       62.58      (4.9%)   -0.6% (  -7% -    6%)
                HighTerm      120.76     (11.6%)      121.21     (14.9%)    0.4% ( -23% -   30%)
{noformat}

This is a "hot" test, with 10M no-stopwords English Wikipedia.  Baseline is normal MMapDir and comp is NativePosixMMapDirectory.  Not sure why some queries are slower ...
                
> Native MMapDir
> --------------
>
>                 Key: LUCENE-3178
>                 URL: https://issues.apache.org/jira/browse/LUCENE-3178
>             Project: Lucene - Core
>          Issue Type: Improvement
>          Components: core/store
>            Reporter: Michael McCandless
>              Labels: gsoc2012, lucene-gsoc-12
>         Attachments: LUCENE-3178-Native-MMap-implementation.patch, LUCENE-3178-Native-MMap-implementation.patch, LUCENE-3178-Native-MMap-implementation.patch
>
>
> Spinoff from LUCENE-2793.
> Just like we will create native Dir impl (UnixDirectory) to pass the right OS level IO flags depending on the IOContext, we could in theory do something similar with MMapDir.
> The problem is MMap is apparently quite hairy... and to pass the flags the native code would need to invoke mmap (I think?), unlike UnixDir where the code "only" has to open the file handle.

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