libjpeg8c vs libjpeg-turbo with libjpeg8 compat on

[Matthias Klose]

On 10/26/2011 10:54 PM, Tom Gall wrote:
> In prep for Linaro Connect & the Ubuntu Developers Summit next week
> I've put together some performance measurements comparing libjpeg8c
> and libjpeg-turbo compiled with it's libjpeg8 compatibility setting.
> Quality settings of 95 and 75 are used. Image sizes used are 640x480
> and 3136x2352.
> 
> Hardware used includes the imx53 QuickStart board by freescale and an
> intel core 2 duo in my Lenovo T400.
> 
> The results can be found here including both the raw numbers and pretty graphs.
> 
> https://wiki.linaro.org/TomGall/LibJpeg8
> 
> It is my hope that at LC/UDS we will be able to use these numbers to
> convince ubuntu to reconsider it's switch to libjpeg8 and instead move
> to libjpeg-turbo. The 2x-4x across the board performance improvement
> story is compelling not to mention the technical side of it as well.

I doubt that Ubuntu will reconsider this for Precise, but I see that you did
schedule a session for UDS/Connect [1]. It would be good, if you could provide
relevant information for the session:

 - performance data from your wiki in a precise/12.04 environment,
   not just for arm, but for all supported Ubuntu architectures.
   Performance data from a natty environment doesn't really help.

   How does this compare to a libjpeg8 targeted to newer CPUs?
   Such a library could be used via hwcap.

 - A test rebuild for packages build-depending on libjpeg*-dev.
   Not sure if this will catch all issues, but it's a start.
   That should give an estimate for sourceful and sourceless
   changes needed, and for which packages you'll have to
   maintain a delta compared to Debian.

Thanks, Matthias

[1] https://blueprints.launchpad.net/libjpeg-turbo/+spec/linaro-gfxmm-libjpeg-turbo