On Wed, 2 Aug 2017, Greg KH wrote: > On Wed, Aug 02, 2017 at 02:17:42PM +0200, Paul Menzel wrote: > > Dear Linux folks, > > > > > > Trying to improve the start-up time of a (slow) ASRock E350M1 which already > > uses coreboot, when instrumenting the time of the Linux Kernel, execution of > > `ohci_pci_init()` takes almost 200 ms. > > > > ``` > > […] > > > [ 0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-4.13.0-rc3+ root=UUID=128529e0-b8bb-4c7d-956d-ddf699036c8c ro noisapnp initcall_debug log_buf_len=32M trace_buf_size=128M trace_clock=global trace_options=nooverwrite,funcgraph-abstime,funcgraph-cpu,funcgraph-duration,funcgraph-proc,funcgraph-tail,nofuncgraph-overhead,context-info,graph-time ftrace=function_graph ftrace_graph_max_depth=2 ftrace_graph_filter=do_one_initcall > > […] > > [ 2.181189] calling ohci_pci_init+0x0/0x1000 [ohci_pci] @ 168 > > [ 2.181268] ohci-pci: OHCI PCI platform driver > > [ 2.182058] ohci-pci 0000:00:12.0: OHCI PCI host controller > > [ 2.182135] ohci-pci 0000:00:12.0: new USB bus registered, assigned bus > > number 3 > > [ 2.182290] ohci-pci 0000:00:12.0: irq 18, io mem 0xf0148000 > > [ 2.244664] usb usb3: New USB device found, idVendor=1d6b, idProduct=0001 > > [ 2.244809] usb usb3: New USB device strings: Mfr=3, Product=2, > > SerialNumber=1 > > [ 2.244879] usb usb3: Product: OHCI PCI host controller > > [ 2.244939] usb usb3: Manufacturer: Linux 4.13.0-rc3+ ohci_hcd > > [ 2.244999] usb usb3: SerialNumber: 0000:00:12.0 > > [ 2.245486] hub 3-0:1.0: USB hub found > > [ 2.245637] hub 3-0:1.0: 5 ports detected > > [ 2.252384] ohci-pci 0000:00:13.0: OHCI PCI host controller > > [ 2.252484] ohci-pci 0000:00:13.0: new USB bus registered, assigned bus > > number 4 > > [ 2.252634] ohci-pci 0000:00:13.0: irq 18, io mem 0xf0149000 > > [ 2.316458] usb usb4: New USB device found, idVendor=1d6b, idProduct=0001 > > [ 2.316604] usb usb4: New USB device strings: Mfr=3, Product=2, > > SerialNumber=1 > > [ 2.316675] usb usb4: Product: OHCI PCI host controller > > [ 2.316733] usb usb4: Manufacturer: Linux 4.13.0-rc3+ ohci_hcd > > [ 2.316793] usb usb4: SerialNumber: 0000:00:13.0 > > [ 2.317666] hub 4-0:1.0: USB hub found > > [ 2.317830] hub 4-0:1.0: 5 ports detected > > [ 2.319124] ohci-pci 0000:00:14.5: OHCI PCI host controller > > [ 2.319199] ohci-pci 0000:00:14.5: new USB bus registered, assigned bus > > number 5 > > [ 2.319341] ohci-pci 0000:00:14.5: irq 18, io mem 0xf014a000 > > [ 2.380239] usb usb5: New USB device found, idVendor=1d6b, idProduct=0001 > > [ 2.380383] usb usb5: New USB device strings: Mfr=3, Product=2, > > SerialNumber=1 > > [ 2.380453] usb usb5: Product: OHCI PCI host controller > > [ 2.380512] usb usb5: Manufacturer: Linux 4.13.0-rc3+ ohci_hcd > > [ 2.380571] usb usb5: SerialNumber: 0000:00:14.5 > > [ 2.381189] hub 5-0:1.0: USB hub found > > [ 2.382135] hub 5-0:1.0: 2 ports detected > > [ 2.382766] initcall ohci_pci_init+0x0/0x1000 [ohci_pci] returned 0 after > > 196766 usecs > > […] > > ``` > > > > It looks like this is not done in parallel, so all the next “tasks” have to > > wait until `ohci_pci_init()` is done. > > > > Do you know of a way to redcuce that time? Please find all the Linux > > messages attached. > > As USB is async for device discovery, this shouldn't be keeping your > boot process from continuing on, right? If you have this as a kernel > module and load it later, it should be fine. > > That being said, look in the driver itself to see what is taking a > while, some devices are just slow to initialize themselves for various > reasons that all are due to the hardware design :( Root-hub initialization tends to be slow, in this case, between 60 and 70 ms. And this system has 3 root hubs. But as Greg says, there's no reason ohci_pci_init() can't be called asynchronously. And there's no reason the driver can't be probed asynchronously. It's just that the device core isn't set up to do this, probably because it causes problems for other kinds of devices. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
