From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:43873) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TLL18-0008DW-6f for qemu-devel@nongnu.org; Mon, 08 Oct 2012 17:37:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TLL17-0000bx-2Y for qemu-devel@nongnu.org; Mon, 08 Oct 2012 17:37:38 -0400 Received: from nm13-vm0.bullet.mail.sp2.yahoo.com ([98.139.91.244]:41513) by eggs.gnu.org with smtp (Exim 4.71) (envelope-from ) id 1TLL16-0000bt-Od for qemu-devel@nongnu.org; Mon, 08 Oct 2012 17:37:37 -0400 From: Shawn Starr Date: Mon, 08 Oct 2012 17:37:30 -0400 Message-ID: <1749009.AR5x9GYHfv@segfault.sh0n.net> In-Reply-To: <50734686.9060004@redhat.com> References: <3321480.8UDes0xfFC@segfault.sh0n.net> <1992746.K6KNzGZOiM@segfault.sh0n.net> <50734686.9060004@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Subject: Re: [Qemu-devel] EHCI USB regression in 1.2.0 - ehci_state_fetchqtd() asserting List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Hans de Goede Cc: Johannes Stezenbach , qemu-devel@nongnu.org, gerd@kraxel.org On Monday, October 08, 2012 11:32:54 PM Hans de Goede wrote: > Hi, > > On 10/08/2012 10:18 PM, Shawn Starr wrote: > > On Monday, October 08, 2012 10:10:49 PM Hans de Goede wrote: > >> Hi, > >> > >> On 10/08/2012 06:11 PM, Johannes Stezenbach wrote: > >> > >> > >> > >> > I also wonder if this is not a generic problem > >>> > >>> for all emulated hw if the driver uses some timeout? > >> > >> Yes it likely is, because the emulated timer interrupt will > >> try to make up for time lost when the vm was not running > >> (in either hypervisor or guest mode), while as hw emulation > >> code which has been pre-empted for what ever reason my > >> simply need some more actual running time before it can > >> complete the task as hand, at which point the timeout > >> will trigger sooner then the hw emulation can handle the > >> task ... > >> > >> Note that with the EHCI emulation we also can have the > >> 2 (guest and hw-emulation time) get out of sync in the > >> other way. When we got behind in processing frames > >> on the periodic schedule compared to "real-time" we would > >> catch up too fast, causing the guest to see large > >> jumps in the frindex register, which it does not like. > >> > >> So all of this really is a precarious balancing act, and > >> to get back to the subject of the thread, the latency > >> spikes some of the kernels debugging options can cause, > >> can upset the balance... > > > > Hello folks, > > > > I am using a non-debug kernel (because debug kernels are seriously > > sluggish). I may elect to get kernel-3.6.0-3.fc18 or kernel-3.6.1-1.fc18 > > from koji also since 3.6 is final now. > > > > Currently using: 3.6.0-0.rc7.git0.1.fc18.x86_64 > > Hmm, so were you using this at the time you hit the bug you reported > earlier too ? And can you reproduce that bug or was it a one > time occurence ? > Need to retry, I triggered this with yahoo IM client in VM. I'll just go to 3.6.1 and try this again this week. When I did trigger this with 3.6.0-0.rc7.git0.1.fc18, it was repeatable. Thanks, Shawn. > Regards, > > Hans