[linux-pm] [dm-devel] dm-crypt low performance
Alan Stern
stern at rowland.harvard.edu
Tue Jan 13 20:00:59 UTC 2009
On Wed, 14 Jan 2009, Ritesh Raj Sarraf wrote:
> Okay!! I think I now have the correct steps to reproduce it consistently.
...
> The above result is from a freshly booted linux with the same suspected faulty
> USB HDD enclosure. I ran it on 2 kernels, one standard and one debug, and both
> gave similar results.
> So shouldn't be faulty hardware.
>
>
> So then with my standard kernel, I booted + hibernated and then resumed and
> then again ran the I/O. Here are the same results.
...
> So this seems to be happening on my laptop when the OS has used the
> hibernation feature. I'm of-course doing a luksClose and USB device
> disconnection before hibernation.
And presumably you reconnect the USB device after resuming. That
reconnect appears to be where the problem arises.
> Here's the usb device listing after hibernation/resume.
>
> rrs at learner:~$ cat /tmp/lsusb.suspend
> Bus 005 Device 005: ID 046d:08c6 Logitech, Inc. QuickCam for DELL Notebooks
> Bus 005 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> Bus 004 Device 007: ID 05e3:0702 Genesys Logic, Inc. USB 2.0 IDE Adapter
> Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
> Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
> Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
> Bus 001 Device 005: ID 046d:c00c Logitech, Inc. Optical Wheel Mouse
> Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Notice that the IDE Adapter is now attached to a 1.1 bus rather than a
2.0 bus. That's why it's running so much slower.
> And here's the usb device listing after a fresh boot.
>
> rrs at learner:~$ lsusb
> Bus 005 Device 004: ID 05e3:0702 Genesys Logic, Inc. USB 2.0 IDE Adapter
> Bus 005 Device 003: ID 046d:08c6 Logitech, Inc. QuickCam for DELL Notebooks
> Bus 005 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
> Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
> Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
> Bus 001 Device 004: ID 046d:c00c Logitech, Inc. Optical Wheel Mouse
> Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Try building a kernel with CONFIG_USB_DEBUG enabled, and post the dmesg
log showing what happens during the disconnect, hibernate, resume, and
reconnect.
You could also try the same thing with no disconnect/reconnect. Just
leave the IDE adapter plugged in the whole time.
Alan Stern
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