On Wed, Oct 03, 2007 at 02:29:49PM +0100, Alan Jenkins wrote: > My internet arrives via a USB 2.0 wireless adaptor. > Using UHCI instead of EHCI saves ~5 wakeup/s: > > With ehci_hcd loaded (and not uhci_hcd): > 31.1% ( 10.0) <kernel core> : ehci_work (ehci_watchdog) > 30.4% ( 9.8) <interrupt> : ehci_hcd:usb5 > > With uhci_hcd loaded (and not ehci_hcd): > 48.0% ( 9.8) <interrupt> : uhci_hcd:usb1 > 19.6% ( 4.0) <kernel module> : usb_hcd_poll_rh_status (rh_timer_func) > > Since ehci_hcd also disagrees with my MP3 player, I'm not sure I want > USB 2.0 any more ;-). I may end up blacklisting the module.
How does it "disagree" with your MP3 player? > I was suprised, since I've read[1] and seem to remember verifying that > UHCI causes a constant 1000 wakeups/s, and that this was unavoidable > given the UHCI specification. I'm running a 2.6.23-rc9-hrt1 kernel > (-rc8-hrt1 patch applied cleanly to -rc9). > > Is this expected? > > Could it be USB autosuspend at work? I've checked and "echo -1 > > /sys/module/usbcoreparamters/autosuspend" doesn't change the number of > wake-ups, but perhaps I'm missing something. It's unlikely that your USB wireless adaptor is being autosuspended. I don't think there's any kernel support for wireless adaptors. There is autosuspend support for USB to ethernet adaptors that run under the kaweth driver. Without kernel support, the device won't autosuspend. > I notice that the number of interrupts is actually the same. The > difference is in the kernel polling routines - ehci_work vs > usb_hcd_poll_rh_status. Does ehci need to poll twice as often, or might > it be possible to tune or hack the polling interval? I haven't read the uhci spec or the code in detail, so I can't give you an easy answer. Perhaps someone on the linux-usb-users list can help. > [1] http://blog.technologeek.org/2007/08/03/71 I do wonder about their claim that the 1000 wakeups per second is inherent to the UHCI spec. Sarah Sharp ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Linux-usb-users@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
