On Wed, Oct 03, 2007 at 09:40:59AM -0700, Sarah Sharp wrote: > 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.
low speed devices like keyboard and mouse are poled by the host. (i don't think this translates to an OS event ever ms, but it does put a sampling rate cap on things) > > > [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 > _______________________________________________ > Discuss mailing list > [EMAIL PROTECTED] > http://mail.lesswatts.org/mailman/listinfo/discuss ------------------------------------------------------------------------- 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
