background or foreground copies, CPU eating

[wwp]

Hello there,


I'm (happily) using mc for years, and performing copies/moves all day
long with it.
What I noticed on my laptop system, is that copying big files (say
stuff like movie files, >250Mb), will often perform quite slowly and
uncomfortably when it's done over USB2. I don't know if it's because of
the USB2 xfer rate (to externals disks, or flash storage "keys"), but I
feel that the system is performing poorly about it: I see the
CPU being normally eaten by MC when it copies the file, then the system
IOWait takes once or twice as long to complete, making the system quite
difficult to use (it takes over user preemption, I hate this): in that
case the best is to stop asking the system for mouse or keyboard
interactions ;-).

Although, I recently tried one thing: make the copy process a background
one. I never used that feature before, and now know that I will always,
at least for such massive copies. In fact, the process takes twice less
CPU and the IOWait-thing is never hanging the system, it can be at
least used at a user lever while the copy is performing, without
glitches! Note that I don't care about the time a copy takes, but I ask
it not to hang the system so that I can still use it.

Could anyone tell me what's the difference between foreground and
background copies? Are background copies being 'niced' down or
low-system prioritized? If so, could that be an option for foreground
copies, to make them more user-friendly?


Regards,

-- 
wwp
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