Date: Sun, 6 Feb 2022 12:02:19 -0700 From: Sean Bruno <sbruno@freebsd.org> To: Warner Losh <imp@bsdimp.com> Cc: freebsd-current <freebsd-current@freebsd.org> Subject: Re: USB Disk Stalls on -current Message-ID: <60ebd011-c2b8-3524-1476-123f11128ffe@freebsd.org> In-Reply-To: <CANCZdfqG-%2B9dfFz-%2BeezZaqbPQN5-mQpw%2B214CkiKC%2B_kmW2ig@mail.gmail.com> References: <7e8459e4-d708-7750-402c-cda2adf6199f@freebsd.org> <CANCZdfqG-%2B9dfFz-%2BeezZaqbPQN5-mQpw%2B214CkiKC%2B_kmW2ig@mail.gmail.com>
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> > > So there's some tools you can use. For usb, there's usbdump that can > get you the USB transactions. I've not used it enough to give more details > here. This will let you know what's going on, and when, on the USB endpoint. > > You can also enable the CAM_IOSCHED stuff. This will allow you to get > latency > measurements for 'requests in the sim' which basically will tell you > what your > latency spread is for the drives. This will tell you if things are > getting caught > up in the USB layer, or after CAM's da driver completes the I/O request > (granted, that's almost certainly not happening, but it will help you > figure out > what's going on and put numbers to the oddities you are seeing). > > Also, make sure you have good cables. I've had lots of hicups over the > years from dodgy USB cables. Also make sure you have good, high quality > enclosures. Many from the USB2 time-period are sketchy at best and I > went through several at one point trying to find a good one. I'd be > tempted to > get USB 3 enclosures. I've had better luck with USB3 gear than USB2 gear > here, but you need a USB-3 controller to get USB-3 speeds which might not > be compatible with the NUC's built-in stuff (though my NUC has one USB3 > port, there's lots of different models). > > Usually, though, I see weirdness associated with dmesg messages from > usb, cam, etc when the hardware is on the sketch end. > > Warner I'm assuming that I have a fairly dodgy USB device, as the pauses seem to correspond to this from CAM being emitted: Feb 6 11:56:43 alice kernel: (da0:umass-sim1:1:0:0): READ(10). CDB: 28 00 36 69 02 6e 00 00 80 00 Feb 6 11:56:43 alice kernel: (da0:umass-sim1:1:0:0): CAM status: CCB request completed with an error Feb 6 11:56:43 alice kernel: (da0:umass-sim1:1:0:0): Retrying command, 2 more tries remain Things resume after this is emitted, but there is a substantial (multiple minutes) pause here. I would assume that timeouts would fire much quicker. sean
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