Re: background or foreground copies, CPU eating

["William Kimber" <williamk orcon net nz>]

Hi,

With Flash drives  aka USB sticks.  The system copies stuff to them then
there is a pause while it gets written to the actual chips  but that is
not the case with USB hard drives.

I have found that the transfer rate is not up to what it is claimed for
USB2 when writing to USB hard drives.  USB3 does seem almost as fast as
writing to internal hard drive.  With SD cards I have found that class 10
are much faster at writing than class 4.

It may also be a function of the OS you are using.  I have a PCLinuxOS
system and until the last kernel upgrade (2.6.38) the swap system used to
be overworked swapping stuff out  and back in again at the same time. 
Swap0 was about 5th busiest process.

Cheers
William

> 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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