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When I start copying files (in my case from hard drive to an USB key), Windows says there are 15 minutes remaining (for example). I then start playing a game which consumes 100% of the CPU's time. I switch the game's priority to 'Low' using the Windows Task Manager. Now when I play for 5 minutes and return to Windows to see if the transfer is making progress, it says there are 10 minutes remaining, but if I stay for a few seconds in Windows it quickly drops to about 2 minutes. What's going on? Bad multitasking?

As a side-note, the game was not loading any files from the hard drive so the hard drive was free for other tasks.

Does anybody know a bit more about the internals of Windows and why this happens?

As a side-note, the game was not loading any files from the hard drive so the hard drive was free for other tasks.

How do you know this? Unless this is some strictly text-based game, it probably loads tons of textures and stuff...also, there is virtual memory it may be using..

(why don't you just take a break from your pc for 10 minutes to let windows copy anyway?)

the whole "minutes/seconds remaining" thing is a horrible estimate, at best

for example, windows assumes every file you copy is the same size, so copying 100 1mb files and one 100gb file will show a few minutes while you're copying the small files and several hours once it gets to the large file

Windows just takes the current copy speed and divides it into the size of all of the remaining files. Some files copy faster than others. Big files usually copy faster than lots of smaller files of the same size. Usually windows 'plays it safe' with the amount of time remaining, at least that is what I have seen with my own experience.

hckr83 wrote:

As a side-note, the game was not loading any files from the hard drive so the hard drive was free for other tasks.

How do you know this? Unless this is some strictly text-based game, it probably loads tons of textures and stuff...also, there is virtual memory it may be using..

Because otherwise the LED of the hard drive constantly flickers on/off but it didn't (it shouldn't anyways because the hard drive is much faster than an USB key).

hckr83 wrote: (why don't you just take a break from your pc for 10 minutes to let windows copy anyway?)

Because I were already playing a game but I just wanted to copy some files, should be possible, no?

EDIT: I also tried making a little program in C that uses 100% of the CPU's time with a never ending while loop (so it doesn't even use the hard drive), but when that program is put at 'Low' priority the copy process really speeds up.

Maybe some threads of the game I was talking about in my first post has some threads running at a higher priority which are still higher than the priority class of the copy process (even when the game is put at 'Low' priority)?