Erik Mouw wrote:
On Tue, Aug 23, 2005 at 04:38:36PM +0530, Rajesh wrote:
I have a case occasionally when I copy data from a usb storage (ipod) to
my hard drive the load average goes up from 0.4 to about 15.0, and the
system becomes very unusable till I kill the cp command. I have checked
the CPU usage, bytes read from usb device, byte written to hard drive
etc, and all these values are low like CPU usage is at a maximum of 30%,
disk read bytes is at an average of 1.5 MiB/s, disk write bytes is at
1.5 MiB/s, number of processes is at 110, etc, during this high load.
1.5 MB/s suggests you're using an IDE drive in PIO mode. Switch to DMA
mode (hdparm -d 1 /dev/hda) and see if it gets any better.
It seems to have helped a little. Now the rate at which load average
goes up has decreased ( I can copy up to about 700-800 MiB compared to a
high of 200MiB earlier), but it is still going up to 15 gradually at
which point I am still killing the cp process to make the system usable.
I know I am not giving much information. But if I know what factors
cause the loadavg to keep on going up I will gladly provide it.
I am running 2.6.12 kernel on a laptop. I have an ipod attached to my
USB 1.1 as a drive on which I am saving and retreiving large
files(2-4GiB files). The transfer speed is slow, but I am fine with it,
as long as the load average stays within bounds so that the machine is
usable. (If I dual boot to windows and do the same operation, I am able
to get the files copied over in a few minutes.). Can vfat be a factor?
Thanks
Rajesh
Erik
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