Before USB

$ dmesg | tail -n 20
[  276.753134] tg3 0000:09:00.0 enp9s0: Link is down
[  276.793551] ata2: port disabled--ignoring
[  276.793828] sd 2:0:0:0: [sda] Starting disk
[  276.830715] rtc_cmos 00:02: System wakeup disabled by ACPI
[  276.867712] dell_wmi: Unknown key e044 pressed
[  276.867739] serial 00:05: activated
[  277.120181] ata5: SATA link down (SStatus 0 SControl 300)
[  277.320215] firewire_core 0000:03:01.4: rediscovered device fw0
[  277.343606] usb 7-1: reset full-speed USB device number 2 using uhci_hcd
[  277.343871] ata1.00: configured for UDMA/33
[  277.780192] usb 7-1.2: reset full-speed USB device number 3 using uhci_hcd
[  277.882143] PM: resume of devices complete after 1135.697 msecs
[  277.882703] PM: Finishing wakeup.
[  277.882705] Restarting tasks ... done.
[  279.303582] ata3: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[  279.320259] ata3.00: configured for UDMA/133
[  649.088678] dell_wmi: Unknown key e043 pressed
[  649.972235] tg3 0000:09:00.0 enp9s0: Link is up at 1000 Mbps, full duplex
[  649.972252] tg3 0000:09:00.0 enp9s0: Flow control is on for TX and on for RX
[ 1067.445556] perf interrupt took too long (2531 > 2495), lowering kernel.perf_event_max_sample_rate to 50100

With USB

$ dmesg | tail -n 20
[  277.320215] firewire_core 0000:03:01.4: rediscovered device fw0
[  277.343606] usb 7-1: reset full-speed USB device number 2 using uhci_hcd
[  277.343871] ata1.00: configured for UDMA/33
[  277.780192] usb 7-1.2: reset full-speed USB device number 3 using uhci_hcd
[  277.882143] PM: resume of devices complete after 1135.697 msecs
[  277.882703] PM: Finishing wakeup.
[  277.882705] Restarting tasks ... done.
[  279.303582] ata3: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[  279.320259] ata3.00: configured for UDMA/133
[  649.088678] dell_wmi: Unknown key e043 pressed
[  649.972235] tg3 0000:09:00.0 enp9s0: Link is up at 1000 Mbps, full duplex
[  649.972252] tg3 0000:09:00.0 enp9s0: Flow control is on for TX and on for RX
[ 1067.445556] perf interrupt took too long (2531 > 2495), lowering kernel.perf_event_max_sample_rate to 50100
[ 1490.050114] usb 2-2: new high-speed USB device number 3 using ehci-pci
[ 1490.282569] usb-storage 2-2:1.0: USB Mass Storage device detected
[ 1490.282706] scsi host5: usb-storage 2-2:1.0
[ 1490.282829] usbcore: registered new interface driver usb-storage
[ 1490.285281] usbcore: registered new interface driver uas
[ 1491.284297] scsi 5:0:0:0: Direct-Access     XXXXXXXX U168CONTROLLER   0.00 PQ: 0 ANSI: 2
[ 1491.289631] sd 5:0:0:0: [sdb] Attached SCSI removable disk