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

Tom_N wrote:

AxelR wrote:

Above all, this explanation does not clarify why 4x CPU power only results in 2x speed

The tests described in this thread did not involve "4x CPU power". They involved the same amount of CPU power (per unit of time), with a workload of one job, or four shorter, "parallel" ones. The first scenario was presumed to be wasting a lot of CPU power, thus the explicitly parallel jobs in the second.

Nobody ever established how many CPU cores a single job uses. E.g., if a single job already made use of 2 real cores, then going to 4 parallel jobs would not make of "4x" as many real cores, since only enough real cores for 2 such jobs would be available. But "only got a 2x speedup because it was using 2 cores before" or "only got a 2x speedup because of the overhead of extra application launches when doing parallel jobs" would be more palatable than "ran parallel jobs and the system still idled 1-2 of the CPUs".

Yes, we need a screen shot of the Task Manager showing CPU graphs to decide. Wanna bet?

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