Re: [Tracker] PATCH: Faster PNG extractor

[Jonatan Pålsson <jonatan palsson pelagicore com>]

On 27 June 2013 16:48, Aleksander Morgado <aleksander lanedo com> wrote:

On 27/06/13 16:26, Jonatan Pålsson wrote:
> To start with, I would like to submit a patch containing a new extractor
> for PNG files, which is faster than the original.
>
> The reason behind the speed increase with this extractor compared to the
> old extractor is that the new extractor seek()s out the metadata fields
> in the PNG, rather than traverse the entire file to find them, as the
> old extractor did (using libpng).

Could you share some numbers on which is the actual speed improvement?
E.g. extracting 1000 random PNGs before took Xs, now it takes Ys.

 

Certainly!

I'm running Tracker on a PandaBoard Rev A4. 1000 replicated PNGs were used, I could make the replicated file available, there is nothing special about it. 

I used the following command to measure the running times:

# For png-faster

tracker-control -r ; echo 3 > /proc/sys/vm/drop_caches ; sync ; sync ; time /usr/lib/tracker/tracker-miner-fs -v 0 --no-daemon

# For the original PNG extractor

tracker-control -r ; /usr/lib/tracker/tracker-extract -m png

echo 3 > /proc/sys/vm/drop_caches ; sync ; sync ; time /usr/lib/tracker/tracker-miner-fs -v 0 --no-daemon

And here are the results:

# png-faster

real    0m14.804s

user    0m4.945s

sys     0m1.313s

# original

real    1m33.274s

user    0m5.250s

sys     0m1.820s

Regards,

Jonatan