[KPhotoAlbum] Load-performance branch

[Robert Krawitz]

On Fri, 8 Jun 2018 02:39:43 +0200, Angel Lopez wrote:
> Oh !!! First thing is that your father gets better.

Thanks!  He's doing well.

> Concerning the software, I discovered, that this option in preferences
> about display thumbnails was not selected:
> "Use embedded image in raw o medium sized raw"
>
> with that option selected speed if ultra/fast (almost instant)

That makes a big difference.  It allows fast JPEG decoding of the
thumbnail.

> Will try the new revision, but with the actual one this appears in console:

You don't need to try that revision; the setting that you found likely
accounts for the entire problem.

> Total files: 857 skipped 0
> Loaded  857  images in  196.089  seconds
>
> by the way, this computer is an old laptop  Celeron 1.2GHz ...

I can't evaluate that number without more context.

Your earlier posting indicated that these are 20 MP images
(5496x3670).  I have a Canon 7DmkII, which produces images of that
size.  RAW files from those are typically around 25 MB.  If the images
are stored on a typical SATA HDD, that works out to about 109 MB/sec,
which is close to the throughput that such disks can typically
sustain.  Since the process of loading images requires that the MD5
checksum be computed, and that requires reading every byte of the
images files, that would suggest that you're I/O-limited, just as you
should be.

I also don't know exactly what processor you're using.  Can you get
the PassMark number for the CPU (https://www.cpubenchmark.net/)?  In
my experience, that usually gives a pretty good rough approximation of
what kind of CPU performance you might expect.

For reference, if I put RAW images on a SATA SSD, I can load about
1500 of them in 100 seconds, or 75 seconds if I increase the number of
scout threads (20 files/sec).  The decoding, EXIF parsing, and MD5
computation results in about 25% total CPU consumption on my system
(which has a PassMark rating a little under 9000); if my I/O system
were fast enough, I might therefore be able to load about 80
files/sec.  Can you watch (with top) how busy your system is while
loading the images?

If you want to go back to current master and see how long it takes to
load images (you'll need to delete index.xml, .thumbnails, and
exif.db), it would make an interesting comparison.
-- 
Robert Krawitz                                     <rlk at alum.mit.edu>

***  MIT Engineers   A Proud Tradition   http://mitathletics.com  ***
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