As I understand USB 2.0 will cause 8000 interrupts in 1 seconds , an interrupt per 125us while read / write will cause some spin lock , specially ,when your write .
And erase 1 nand block will cause several millisecond so when you write the usb stick . you always get no useful spin lock wait , but you can not skip it what you can do is Buy a faster speed usb stick . [?] 2015-01-18 1:01 GMT+08:00 Jan Stanstrup <stanst...@gmail.com>: > Hi. > > > I am running ubuntu on BBB rev C and I have a USB disk attached. I am > having trouble accessing large files on the USB disk over sftp and ftp. > When I start a transfer it starts fine but after some minutes CPU is at > 100% and the transfer slows to a crawl. I have tried different ftp servers > but it makes no difference. > > I think I have narrowed the problem down to a problem of reading from the > USB disk. > > If I make a large file: > dd if=/dev/zero of=file.txt count=1024 bs=4000000 > (which seem to be no problem) > and try to read it with > time sh -c "dd if=file.txt bs=4k" > the same thing happens. After a while CPU reaches 100%. > > I have tried using nice and oinice on the process but it doesn't help. > > I found a discussion of a similar problem ( > https://bbs.archlinux.org/viewtopic.php?id=112846&p=4) where it was > suggested to set /sys/kernel/mm/transparent_hugepage/defrag to madvise. > But I could not figure out how to do that on the BBB (transparent_hugepage > doesn't exist and cannot be created). > > Any ideas for what I can do? > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to beagleboard+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
