From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Malone Subject: Re: serial problems cont.. Date: Tue, 02 Sep 2008 13:25:57 +1200 Message-ID: <48BC9625.1010103@tait.co.nz> References: <48BB059E.1050600@tait.co.nz> <48BBB558.6060909@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset=ISO-8859-1 Content-Transfer-Encoding: 7BIT Cc: Avi Kivity To: kvm mailing list Return-path: Received: from gatekeeper.tait.co.nz ([202.37.96.11]:45213 "EHLO gatekeeper.tait.co.nz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751517AbYIBB0D (ORCPT ); Mon, 1 Sep 2008 21:26:03 -0400 Received: from gatekeeper.tait.co.nz (localhost.localdomain [127.0.0.1]) by localhost.tait.co.nz (Postfix) with ESMTP id 8456446755 for ; Tue, 2 Sep 2008 13:26:01 +1200 (NZST) Received: from sunstrike.tait.co.nz (sunstrike [172.25.40.92])by gatekeeper.tait.co.nz (Postfix) with ESMTP id 7105446752for ; Tue, 2 Sep 2008 13:26:01 +1200 (NZST) Received: from conversion-daemon.sunstrike.tait.co.nz by sunstrike.tait.co.nz(Sun Java System Messaging Server 6.1 (built Apr 28 2004))id <0K6J00B01L16XN00@sunstrike.tait.co.nz>(original mail from michael.malone@tait.co.nz) for kvm@vger.kernel.org; Tue,02 Sep 2008 13:26:01 +1200 (NZST) In-reply-to: <48BBB558.6060909@qumranet.com> Sender: kvm-owner@vger.kernel.org List-ID: Avi Kivity wrote: > Michael Malone wrote: >> Hi everyone, >> >> I've written a couple of questions regarding the serial device in >> KVM. After slightly more investigation I think I have found what's >> going awry. Correct me if I'm wrong, but I believe that KVM >> generates an interrupt for every single character it sends through >> the serial port. This throws CPU usage through the roof and I >> suspect this means that the timers aren't being handled correctly and >> it failed on a string of 0's for me due to the timing slips. >> GNU/Linux and Windows don't have anywhere near the processor usage >> for their serial ports. Now, I know nothing of serial programming >> and don't have any time to investigate it too heavily just now, but I >> have pulled down the source and had a look through that, but it looks >> to be doing the right thing (I suppose?). I was mainly wondering >> how GNU/Linux and windows handle serial interrupts or if some of the >> serial character events could be buffered, rather than overload the >> processor? I guess this is a low priority for you, but any help >> would be greatly appreciated (And when I have some more time, I will >> spend some of it helping to develop KVM! Quid pro quo, Clarice...) >> > > What version of kvm are you testing? There were some changes to the > serial emulation recently. See for example > 02f0b4c0cc26f3a2578d515d96781f5a6258888d in kvm-73. > I have tried with kvm 62, 69, 72 and 74. All of them gave the same result. What do you mean by "See for example 02f0b4c0cc26f3a2578d515d96781f5a6258888d"? - I am running Ubuntu 8.04 (Hardy) as host and Windows XP as guest on an Intel Core 2 duo processor. ======================================================================= This email, including any attachments, is only for the intended addressee. It is subject to copyright, is confidential and may be the subject of legal or other privilege, none of which is waived or lost by reason of this transmission. If the receiver is not the intended addressee, please accept our apologies, notify us by return, delete all copies and perform no other act on the email. Unfortunately, we cannot warrant that the email has not been altered or corrupted during transmission. =======================================================================