[jira] [Resolved] (IMPALA-2887) improve Bitmap with a fast mod

["Tim Armstrong (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IMPALA-2887?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Tim Armstrong resolved IMPALA-2887.
-----------------------------------
    Resolution: Won't Fix

The code around this has changed a lot, unclear if this is still important.

> improve Bitmap with a fast mod
> ------------------------------
>
>                 Key: IMPALA-2887
>                 URL: https://issues.apache.org/jira/browse/IMPALA-2887
>             Project: IMPALA
>          Issue Type: Improvement
>          Components: Backend
>    Affects Versions: Impala 2.3.0
>            Reporter: Zuo Wang
>            Priority: Minor
>              Labels: performance
>
> The probe filter is fairly expensive. check the profile below.
> This is due to the mod operator in Bitmap::Get<true>.
> I will try to implement a fast mod according to "Division by Invariant Integers Using Multiplication"(T. Granlund and P. L. Montgomery, https://gmplib.org/~tege/divcnst-pldi94.pdf) 
> Function Stack Effective Time by Utilization Spin Time Overhead Time Effective Time Spin Time Overhead Time Instructions Retired: Total Instructions Retired: Self CPI Rate: Total CPI Rate: Self CPU Frequency Ratio: Total CPU Frequency Ratio: Self Module Function (Full) Source File Start Address
> Total 98.9% 1.1% 0.0% 0.0% 0s 0s 100.0% 0 0.496 0.000 1.080 0.000
> impala::HdfsParquetScanner::ScalarColumnReader<long, (bool)1>::ReadNonRepeatedValue 42.7% 0.0% 0.0% 4.1% 0s 0s 66.0% 1,944,000,000 0.329 1.041 1.108 1.081 impalad impala::HdfsParquetScanner::ScalarColumnReader<long, (bool)1>::ReadNonRepeatedValue(impala::MemPool*, impala::Tuple*, bool*) hdfs-parquet-scanner.cc 0xbf1560
> ReadValue<false> 38.6% 0.0% 0.0% 0.0% 0s 0s 64.1% 14,400,000 0.307 0.250 1.111 impalad ReadValue<false> hdfs-parquet-scanner.cc 0xbf156d
> ReadSlot<false> 37.8% 0.0% 0.0% 7.4% 0s 0s 64.0% 4,989,600,000 0.302 0.768 1.116 1.139 impalad ReadSlot<false> hdfs-parquet-scanner.cc 0xbf15a2
> Get<true> 26.6% 0.0% 0.0% 26.6% 0s 0s 52.4% 52,192,800,000 0.259 0.259 1.114 1.114 impalad Get<true> bitmap.h 0xbf15e2



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