Messages in this thread | | | Subject | Re: USB disk speed regression WD Elements - with bisect result 22547c4cc4fe20698a6a85a55b8788859134b8e4 | From | Zdenek Kabelac <> | Date | Tue, 25 Jul 2017 16:34:09 +0200 |
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Dne 25.7.2017 v 16:25 Alan Stern napsal(a): > On Tue, 25 Jul 2017, Zdenek Kabelac wrote: > >> Dne 24.7.2017 v 16:41 Alan Stern napsal(a): >>> On Mon, 24 Jul 2017, Zdenek Kabelac wrote: >>> >>>> Hi >>>> >>>> I've problem with my USB storage devices: WD Elements 1TB. >>>> (Bus 004 Device 002: ID 1058:10a8 Western Digital Technologies, Inc. Elements >>>> Portable (WDBUZG)) >>>> >>>> >>>> After kernel >4.9 when disk is attached via cable it has very low speed >>>> (less then 1MB/s). >>>> >>>> It can run at full speed (>22MB/s) when the Linux kernel is fully rebooted (so >>>> disk is attached during the reboot of Lenovo T61, C2D, Fedora Rawhide). >>>> >>>> However when >4.9 kernel is running and disk is just attached it's very slow. >>>> >>>> I've played a bisect game - and the clean result has been: >>>> >>>> 22547c4cc4fe20698a6a85a55b8788859134b8e4 >>>> >>>> When I just revert this patch with 4.13-rc1 - it's again running with full >>>> speed even when disk is attached (thus no reboot is needed for full speed). >>>> >>>> >>>> So while I've no idea what 22547c4cc4fe20698... is doing, it seems to have >>>> some unpleasant side-effect on regular USB devices. >>>> >>>> So what else is needed to get this properly working ? >>>> (assuming plain revert of 22547c4cc4fe20698 is unwanted). >>>> >>>> What more info can I provide to get this storage 'normally' usable without >>>> rebooting the machine. >>> >>> Please post the dmesg logs showing what happens when the disk is >>> first attached and operates slowly, and what happens when the disk is >>> attached following a reboot and operates normally. >> >> So I'm attaching kernel traces from kernel 4.8 & 4.12 from T61. >> >> Both are from full boot (all kernel: messages) >> >> In both cases - boot was with USB WD disk attached - >> then I've detached USB disk and reattached again. >> >> On 4.8 this had normal speed all the time >> On 4.12 after reattach -> slow speed. >> >> I should also add that on Lenovo T440s - there seems to be NO slowdown >> when this WD Element drive is attached it works normally all the time. >> >> So it could be probably related to USB chipset on T61 ?? >> >> For completeness I'm also attaching boot kernel trace from T440s where USB >> disk is just attached and works with normal speed. > > The log shows that the drive is reconnecting at full speed (12 Mb/s) > instead of high speed (480 Mb/s), which is why the communication > becomes so slow. > > I think there's some weird timing issue going on. Hard to tell from > just the log, though. > > Please collect a usbmon trace, starting from just before the unplug and > ending after the drive has reconnected at the slower speed. > Instructions are in Documentation/usb/usbmon.txt. Use bus number 0 for > the trace, so we can see what's going on with both the high-speed and > full-speed connections. And collect traces for both 4.8 and 4.12. > > And try to avoid using any other USB devices during the test, to > minimize the amount of excess information recorded in the trace. >
Ahh nice spot - I've not been checking that message in detail - so maybe I should actually run another bisect - where:
"new high-speed USB device number..."
turned into:
"new full-speed USB device number 2 using uhci_hcd" "not running at top speed; connect to a high speed hub"
As I've just ended with a commit that made 'slow-speed' reality but I need to find the commit having impact on connecting message
Zdenek
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