LJH wrote:
This is interesting JJmack. Good to see that an actual situation has been used to show that Photoshop does indeed use system resource, outside the available RAM. What is alarming is that Adobe actually state that Photoshop will use RAM first, before the available scratch disk allowance. Perhaps it does but only for less demanding tasks.
The way that Photoshop virtual memory (scratch disk) works is a SD is allocated upon launch. Depending on how much ram you have, the SD temp file can be as large as the ram allocated to Photoshop. This is done so that the "ram first" use can seamlessly transition to ram + SD. Once that initial SD is set up, opening images also increases the SD allocation (in the background as long as the image fits in ram). Open multiple images also increases SD allocation. Also note that History states adds to the SD allocation. Each history state is written (in the background) to the SD. As log as your efficiency stays at 100%, the SD is only written to as needed, in the background. Once your efficiency starts to drop, tat background writing turns into a foreground opperation and when that happens, Photoshop slows down. Below 80% is noticeably slower, if you drop further, it gets even worse.. And, actually,Photoshop does indeed relinquish allocated ram at the request of the OS. They way hat works varies depending on Mac & Windows. Reallocation can take a while on either OS and it only happens when another apps requests ram from the OS. So, it can look like Photoshop is hoarding allocated ram but it's not...it just keeps it unless the OS demands it back–and it's not immediate either.
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