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[Octave-bug-tracker] [bug #54100] fread using SKIP larger than zero is e
From: |
Dan Sebald |
Subject: |
[Octave-bug-tracker] [bug #54100] fread using SKIP larger than zero is extremely slow |
Date: |
Mon, 23 Jul 2018 05:08:24 -0400 (EDT) |
User-agent: |
Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0 |
Follow-up Comment #15, bug #54100 (project octave):
Here's the latest development result (similar to the result you listed):
octave:21> fid = fopen("zeros1000by61.dat","r");
octave:22> tic; xt = fread (fid, [1000, 60], 'single'); toc
Elapsed time is 0.0011611 seconds.
octave:23> fclose(fid);
octave:24> fid = fopen("zeros1000by61.dat","r");
octave:25> tic; xt = fread (fid, [1000, 60], 'single', 4); toc
Elapsed time is 0.0222042 seconds.
I'm attaching a *very* crude implementation of the post-read large buffer
condensation method. It may crash for the non-skip case right now, but I'm
just trying to illustrate the improvement in speed for the skip case:
octave:1> fid = fopen("ramp1000by61.dat","r");
octave:2> tic; xt = fread (fid, [1000, 60], 'single', 4); toc
block_size: 1
N_block: 60000
Elapsed time is 0.00137806 seconds.
octave:3> xt(1,:)
ans =
Columns 1 through 16:
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29
31
Columns 17 through 31:
33 35 37 39 41 43 45 47 49 51 53 55 57 59 61
octave:4> size(xt)
ans =
1000 31
(file #44607)
_______________________________________________________
Additional Item Attachment:
File name: octave-fread_crude_large_hunk_prototype-djs2018jul22.diff Size:3 KB
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- [Octave-bug-tracker] [bug #54100] fread using SKIP larger than zero is extremely slow, Rik, 2018/07/20
- [Octave-bug-tracker] [bug #54100] fread using SKIP larger than zero is extremely slow, Dan Sebald, 2018/07/20
- [Octave-bug-tracker] [bug #54100] fread using SKIP larger than zero is extremely slow, Rik, 2018/07/22
- [Octave-bug-tracker] [bug #54100] fread using SKIP larger than zero is extremely slow, Rik, 2018/07/23
- [Octave-bug-tracker] [bug #54100] fread using SKIP larger than zero is extremely slow, Dan Sebald, 2018/07/23
- [Octave-bug-tracker] [bug #54100] fread using SKIP larger than zero is extremely slow,
Dan Sebald <=
- [Octave-bug-tracker] [bug #54100] fread using SKIP larger than zero is extremely slow, Rik, 2018/07/23
- [Octave-bug-tracker] [bug #54100] fread using SKIP larger than zero is extremely slow, Dan Sebald, 2018/07/24
- [Octave-bug-tracker] [bug #54100] fread using SKIP larger than zero is extremely slow, Rik, 2018/07/24
- [Octave-bug-tracker] [bug #54100] fread using SKIP larger than zero is extremely slow, Dan Sebald, 2018/07/29
- [Octave-bug-tracker] [bug #54100] fread using SKIP larger than zero is extremely slow, Rik, 2018/07/29
- [Octave-bug-tracker] [bug #54100] fread using SKIP larger than zero is extremely slow, Dan Sebald, 2018/07/29