Hi,
I have two similar linux machines with legacy PCI / USB 3.0 cards plugged in. These use the NEC uPD720200 USB 3.0 Host Controller and the xhci module.
System A "Fast": **************** USB 3.0 read performance of about 80 MB/s doesn't need pci=nomsi to see the USB 3.0 devices
Snips of lspci -vv : -------------------- Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx+
Interrupt: pin A routed to IRQ 21
Region 0: Memory at febfe000 (64-bit, non-prefetchable) [size=8K]
Capabilities: [90] MSI-X: Enable+ Count=8 Masked- Capabilities: [a0] Express (v2) Endpoint, MSI 00 DevSta: CorrErr+ UncorrErr- FatalErr- UnsuppReq+ AuxPwr- TransPend-
Capabilities: [100] #1033
System B "Slow": **************** USB 3.0 read performance of about 40 MB/s needs pci=nomsi to see the USB 3.0 devices
Snips of lspci -vv : -------------------- Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
Interrupt: pin A routed to IRQ 17
Region 0: Memory at fb000000 (64-bit, non-prefetchable) [size=8K]
Capabilities: [90] MSI-X: Enable- Count=8 Masked-
Capabilities: [a0] Express (v2) Endpoint, MSI 00 DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq- A
Is it likely that the kernel option is what's dropping the USB 3.0 performance to about 1/2 speed?
If there is a suggestion to up the speed please let me know.
--- John