[Octave-bug-tracker] [bug #40304] Excessive I/O in load function

[Mike Miller]

Update of bug #40304 (project octave):

                  Status:                    None => Need Info              

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Follow-up Comment #5:

I don't see the same set of calls with a text file created by Octave in the
current development version. Can you upload the file or a similar text file
that shows the behavior to this bug tracker?

Here's what I see:


open("x", O_RDONLY)                     = 3
fstat(3, {st_mode=S_IFREG|0640, st_size=318768434, ...}) = 0
lseek(3, 0, SEEK_SET)                   = 0
read(3, "# Create", 8)                  = 8
lseek(3, 512, SEEK_SET)                 = 512
read(3, "11792406", 8)                  = 8
lseek(3, 1024, SEEK_SET)                = 1024
read(3, "80921890", 8)                  = 8
### cut 37 lines
close(3)                                = 0
open("x", O_RDONLY)                     = 3
read(3, "# Created by Octave 3.7.7+, Sun "..., 8191) = 8191
close(3)                                = 0
open("x", O_RDONLY)                     = 3
read(3, "# Created by Octave 3.7.7+, Sun "..., 8191) = 8191
lseek(3, 0, SEEK_SET)                   = 0
read(3, "# Created by Octave 3.7.7+, Sun "..., 8191) = 8191
lseek(3, 0, SEEK_SET)                   = 0
lseek(3, 116, SEEK_SET)                 = 116
read(3, "ns: 4096\n 0.4302984744815452 0.3"..., 8191) = 8191
lseek(3, 124, SEEK_SET)                 = 124
read(3, "\n 0.4302984744815452 0.306896574"..., 8191) = 8191
lseek(3, 0, SEEK_SET)                   = 0
read(3, "# Created by Octave 3.7.7+, Sun "..., 8191) = 8191
close(3)                                = 0
open("x", O_RDONLY)                     = 3
read(3, "# Created by Octave 3.7.7+, Sun "..., 8191) = 8191
mmap(NULL, 134221824, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
= 0x7f53c74e2000
lseek(3, 0, SEEK_CUR)                   = 8191
lseek(3, 0, SEEK_CUR)                   = 8191
lseek(3, 0, SEEK_CUR)                   = 8191


and so on.

The first 3 opens are for file format detection, the 4th open is when the file
is actually read into Octave. While the file is being read, there are about
432 lseeks with zero offset for every read of 8191 bytes. I don't see any
lseeks with negative offset.

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