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bug#13127: [PATCH] cut: use only one data strucutre
From: |
Cojocaru Alexandru |
Subject: |
bug#13127: [PATCH] cut: use only one data strucutre |
Date: |
Tue, 11 Dec 2012 15:24:36 +0100 |
On Sun, 09 Dec 2012 21:45:03 +0100
Jim Meyering <address@hidden> wrote:
> Thanks for the patch.
> This is large enough that you'll have to file a copyright assignment.
> For details, see the "Copyright assignment" section in the file
> named HACKING.
Fine.
> Have you considered performance in the common case?
> I suspect that a byte or field number larger than 1000 is
> not common. That is why, in the FIXME comment above,
> I suggested to use an adaptive approach. I had the feeling
> (don't remember if I profiled it) that testing a bit per
> input field would be more efficient than an in-range test.
Yes, it was the first thing I checked. And there's no performance loss.
> If you construct test cases and gather timing data, please do so
> in a reproducible manner and include details when you report back,
> so we can compare on different types of systems.
Here are my benchmarks:
OS: Parabola GNU/linux-libre (linux-libre v3.6.8-1)
Compiler: GCC 4.7.2
Cflags: -O2
LANG: C
CPU: Intel Core Duo (1.86 GHz) (L1 Cache 64KiB) (L2 Cache 2MiB)
Main memory:
- Bank 0: DIMM DRAM Synchronous (1GiB) (width 64 bits)
- Bank 1: DIMM DRAM Synchronous (1GiB) (width 64 bits)
NOTE: information gathered with `lshw'.
Summary (see the attached file for complete data):
### small ranges
cut-pre: 0:01.84
cut-post: 0:01.36
cut-split: 0:01.25
### bigger ranges
cut-pre: 0:11.74
cut-post: 0:09.20
cut-split: 0:07.91 ***
### fields
cut-pre: 0:02.90
cut-post: 0:02.68
cut-split: 0:02.85
### --output-delimiter
cut-pre: 0:02.90
cut-post: 0:02.74
cut-split: 0:02.80
NOTES:
cut-pre is the current implementation and was compiled from commit ec48beadf.
cut-post was compiled after applying the above patch to commit ec48beadf.
cut-split was compiled after applying the `split-print_kth' patch to commit
ec48beadf.
The main advantages cames from splitting `print_kth' into two
separate functions, so now `print_kth' does fewer checks.
Best regards,
Cojocaru Alexandru
full-data.txt
Description: Text document
split-print_kth
Description: Binary data