I meddled around with this last week via the Fedora ARM list, it was simple to reproduce that pinging the Panda Ethernet from another machine on the local network with -i0.001 yielded an effective 50% increase in USB storage throughput at the Panda compared to it being left idle.
Neither RUNTIME_PM (suggested by Felipe Balbi at TI) nor USB_SUSPEND were to blame since the issue stayed the same with those deconfigured. It seems the issue may be to do with the Panda's hub / ethernet chip idle / wakeup characteristics but since there are no hub registers in there settable from Panda side AFAIK (there are some settable in the missing EEPROM that can configure the hub / Ethernet bridge) I am out of ideas to follow it up. -- You received this bug notification because you are a member of Linaro Release Team, which is a direct subscriber. https://bugs.launchpad.net/bugs/709245 Title: panda: USB disk IO slow Status in Linaro Linux: Confirmed Bug description: My Panda's USB seems to be significantly slower than a Beagle C4. hdparm shows buffered reads as ~12MB/s on the Panda, and about ~20-25MB/s on a Beagle C4 from the same external Lacie USB disk. Kernel is 2.6.37-1002-linaro-omap Disk shows as: [ 5.170440] scsi 0:0:0:0: Direct-Access LaCie d2 quadra PQ: 0 ANSI: 4 [ 5.172546] sd 0:0:0:0: Attached scsi generic sg0 type 0 [ 5.175415] sd 0:0:0:0: [sda] 976773168 512-byte logical blocks: (500 GB/465 GiB) The board is otherwise idle during the test. Doing perf_2.6.37-12 record -a dd if=/dev/sda of=/dev/null bs=4096 count=100000 shows : 81.41% swapper [kernel.kallsyms] [k] default_idle 6.33% dd [kernel.kallsyms] [k] __copy_to_user 0.94% swapper [kernel.kallsyms] [k] cpu_idle 0.51% dd [kernel.kallsyms] [k] __make_request 0.51% perf_2.6.37-12 [kernel.kallsyms] [k] __copy_from_user which suggests it's not CPU constrained. Dave _______________________________________________ Mailing list: https://launchpad.net/~linaro-release Post to : [email protected] Unsubscribe : https://launchpad.net/~linaro-release More help : https://help.launchpad.net/ListHelp
