Adobe Lightroom Parallel Processing Speeds Up JPEG Export by 50%

Started Mar 5, 2013 | Discussions thread
AxelR Senior Member • Posts: 1,169
Re: Adobe's goal isn't export speed

RedFox88 wrote:

I read a statement from Adobe that their goal in exporting images is not to do so at the fastest speed possible. They do this so the user can still keep developing images within LR instead of having the program unusable by the user until the export is complete. This is multi-tasking: not doing everything super fast to enable everything to be in use.

AxelR wrote:

Considering that, 14 minutes to export 1600 unprocessed JPEG files from EOS MkIII raws is *excruciatingly* slow on such a nice and fast i7 SSD box as yours: properly written software can get away with such a task in less than 3 minutes.

A good-sounding explanation is not an excuse for bad design. Resource allocation - such as how and where to spend CPU power - is an Operating System thing: features like automatic interactive task priority boost, and thread priorities that can be set by the application developer to give the interactive tasks clear precedence over the background tasks should take care of that, and when done properly a background task like export can still run as fast as possible and use all the available power without bogging-down the interactive tasks.

Above all, this explanation does not clarify why 4x CPU power only results in 2x speed: even under the very unlikely hypothesis that LR "reserves" some percentage of CPU cycles just in case, 4x more cycles should still result in 4x more speed. No matter how much is allegedly "set apart", CPU-bound tasks should still scale quite linearly with increasing CPU power, until I/O (or in some cases memory bandwidth) starts to becomes a bottleneck.

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