On Sat, 16 Jun 2007, manoj mathai wrote: > On 6/6/07, Alan Stern <[EMAIL PROTECTED]> wrote: > > Can you find out which process is using a lot of CPU time? Or do you > > think the problem is simply that too much memory is being used for > > buffers? > > i ran 'top' this time when i was performing the transfer. the 'wa' io/wait > field in the CPU line always shows a value above 95% and the peak kernel > load was around 9. the kernel load is maximum at the end of the transfer. > the process ' usb-storage' which i think is responsible for the transfer was > hardly using any CPU
> > What you need to do is reduce the amount of memory used for I/O > > buffers. However I don't know how you can control it. Maybe people on > > LKML can provide some advice. > > yes, think too much memory is being used for i/o buffers. even when i > transfer data within my hard disk, the sys mon applet clearly shows the i/o > buffers using the entire amount of free RAM available. but during hard disk > to hard disk data transfer, the cpu usage and load is minimal. when i > transfer data to my pen drive, its quite high. Do you find that the computer is more responsive to the keyboard and mouse when you do the hard disk test than when you do the USB transfer? > it takes around 20 minutes to copy 2G of data to my pen drive. the file > transfer prg (nautilus) itself takes 20 minutes. after that, when i unmount > my drive using nautilus, it takes another 2-3 minutes. i can see the drive's > light blinking during those 2-3 minutes which indicates data transfer. but, > this extra time taken while unmounting is random and rare. most of the time, > it doesn't take any time. > > i have also attached a screen shot of the gnome sys monitor applet showing > high kernel load during the transfer. I don't know how to solve your I/O buffer problem -- assuming it really is a problem, which it might not be. It's possible that the high CPU usage is caused by hardware problems in the USB controller. Other people using VIA hardware have reported similar things. Can you try running a similar test on a different computer? Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
