From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1JCI2E-0007RX-KI for qemu-devel@nongnu.org; Tue, 08 Jan 2008 12:14:42 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1JCI2C-0007P4-HI for qemu-devel@nongnu.org; Tue, 08 Jan 2008 12:14:41 -0500 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1JCI2C-0007Om-4C for qemu-devel@nongnu.org; Tue, 08 Jan 2008 12:14:40 -0500 Received: from il.qumranet.com ([82.166.9.18]) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1JCI2B-00016T-Iq for qemu-devel@nongnu.org; Tue, 08 Jan 2008 12:14:39 -0500 Message-ID: <4783AF65.8090908@qumranet.com> Date: Tue, 08 Jan 2008 19:14:13 +0200 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH] USB 2.0 EHCI emulation References: <64F9B87B6B770947A9F8391472E0321610478FD1@ehost011-8.exch011.intermedia.net> <200801080130.04161.paul@codesourcery.com> <1199781789.4421.7.camel@localhost.localdomain> <200801081531.27719.paul@codesourcery.com> In-Reply-To: <200801081531.27719.paul@codesourcery.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Arnon Gilboa Paul Brook wrote: > On Tuesday 08 January 2008, Dor Laor wrote: > >> On Tue, 2008-01-08 at 01:30 +0000, Paul Brook wrote: >> >>>> -The host kernel was configured with dynamic tick & hi-res timers, to >>>> allow the desired timer resolution. USB 2.0 microframe is 125usec. >>>> >> It still works even without accurate timing demands. >> Only isochronous mode will have problems and it is not yet supported for >> ehci. >> > > It could also cause problems for periodic interrupt transfers. It's not > uncommon for linux hosts to have a minimum timer period of 10ms (100Hz). This > means the periodic list will be traversed 80x slower than it should, so a > typical for a mouse or tablet with a 10ms poll interval will only be polled > every 800ms. 800ms lag on a mouse is unacceptable. > > The existing USB hosts have similar issues. However the problem is an order of > magnitude less severe, so isn't noticeable under normal circumstances. > > Surely qemu should read the time and adjust? For example, a 1000Hz guest running on a 100Hz host will see a 10x slowdown in real time. -- error compiling committee.c: too many arguments to function