From mboxrd@z Thu Jan 1 00:00:00 1970 From: "David S. Ahern" Subject: Re: high load with usb device Date: Tue, 14 Sep 2010 10:45:32 -0600 Message-ID: <4C8FA6AC.6080804@cisco.com> References: <4C80E839.50604@msgid.tls.msk.ru> <4C8A1AE3.8030705@redhat.com> <4C8A2187.1020202@msgid.tls.msk.ru> <4C8A59FE.9090400@msgid.tls.msk.ru> <4C8C9CAA.9030203@redhat.com> <4C8F1B54.60604@msgid.tls.msk.ru> <4C8F3B00.3000703@redhat.com> <4C8F3BA7.7060302@redhat.com> <4C8F47A1.4030600@msgid.tls.msk.ru> <4C8F497C.7000904@redhat.com> <4C8F4DA8.50606@msgid.tls.msk.ru> <4C8F50E1.3060704@redhat.com> <4C8F563E.6070701@msgid.tls.msk.ru> <4C8F757D.1010509@msgid.tls.msk.ru> <4C8F77C1.90509@redhat.com> <4C8F78D6.2060808@msgid.tls.msk.ru> <4C8F8AA2.90403@redhat.com> <4C8F8C5A.9000003@msgid.tls.msk.ru> <4C8F9C23.4090400@redhat.com> <4C8FA2D6.1090604@msgid.tls.msk.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Avi Kivity , KVM list To: Michael Tokarev Return-path: Received: from sj-iport-5.cisco.com ([171.68.10.87]:23982 "EHLO sj-iport-5.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752354Ab0INQpe (ORCPT ); Tue, 14 Sep 2010 12:45:34 -0400 In-Reply-To: <4C8FA2D6.1090604@msgid.tls.msk.ru> Sender: kvm-owner@vger.kernel.org List-ID: On 09/14/10 10:29, Michael Tokarev wrote: > For comparison, here's the same strace stats without -usbdevice: > > % time seconds usecs/call calls errors syscall > ------ ----------- ----------- --------- --------- ---------------- > 97.70 0.080237 22 3584 select > 1.09 0.000895 0 6018 3584 read > 0.33 0.000271 0 9670 clock_gettime > 0.31 0.000254 0 6086 gettimeofday > 0.26 0.000210 0 2432 rt_sigaction > 0.17 0.000137 0 3653 timer_gettime > 0.15 0.000122 0 2778 timer_settime > 0.00 0.000000 0 1 ioctl > 0.00 0.000000 0 1 rt_sigpending > 0.00 0.000000 0 1 1 rt_sigtimedwait > ------ ----------- ----------- --------- --------- ---------------- > 100.00 0.082126 34224 3585 total > > Yes, it is still doing lots of unnecessary stuff, but the load > is <1%. Without a USB device attached the controller is turned off. See the call to qemu_del_timer() in uhci_frame_timer(). As soon as you add the tablet device the polling starts (see qemu_mod_timer in uhci_ioport_writew) and the cpu load starts. David > > (This is without host_alarm_handler() in qemu_notify_event()) > > /mjt > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >