On Thu, Jan 02, 2014 at 04:01:29PM -0500, Mark Lord wrote: > On 14-01-02 02:15 PM, Sarah Sharp wrote: > > On Tue, Dec 31, 2013 at 12:40:16PM -0800, walt wrote: > .. > >> Unfortunately this patch causes a regression when copying large files to my > >> outboard USB3 drive. (Nothing at all to do with networking.) > >> > >> When I try to copy a large (20GB) file to the USB3 drive, the copy dies after > >> about 7GB, the ext4 journal aborts and the drive is remounted read-only. > >> > >> This bug is 100% reproducible (always pretty close to 7GB) and reverting this > >> patch completely fixes the problem. > > > > Ok, I had feared that would be a consequence of this patch. I think the > > problem is that the usb-storage driver submitted an URB with more > > scatter-gather entries than would fit on the ring segment, the xHCI > > driver rejected the URB with -ENOMEM, and the SCSI core eventually gave > > up on the SCSI command. > > Is there not a block layer / scheduler tunable for max sg entries or something? There is a USB host controller tunable for max number of sg entries that's passed up to the SCSI or block layer. We discussed changing it, but there wasn't a good consensus on what to change it to: http://marc.info/?l=linux-usb&m=138496358223904&w=2 http://marc.info/?l=linux-netdev&m=138496706007262&w=2 In the end, we thought we didn't need to limit the sglist size because Paul thought usb-storage limits the overall transfer size to 120K, which should fit in 31 TRBs: http://marc.info/?l=linux-usb&m=138498190419312&w=2 Walt, could you see if limiting the sglist size helps, by setting hcd->self.sg_tablesize in xhci.c to 31? Sarah Sharp -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
