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 10:09:18 -0600 Message-ID: <4C8F9E2E.5060003@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> <4C8F99FF.8060808@cisco.com> <4C8F9C14.9070509@msgid.tls.msk.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Avi Kivity , KVM list To: Michael Tokarev Return-path: Received: from rtp-iport-1.cisco.com ([64.102.122.148]:62122 "EHLO rtp-iport-1.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754149Ab0INQJ1 (ORCPT ); Tue, 14 Sep 2010 12:09:27 -0400 In-Reply-To: <4C8F9C14.9070509@msgid.tls.msk.ru> Sender: kvm-owner@vger.kernel.org List-ID: On 09/14/10 10:00, Michael Tokarev wrote: > 14.09.2010 19:51, David S. Ahern =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >> cat /sys/devices/system/clocksource/clocksource0/current_clocksource >=20 > It's tsc (AthlonII CPU). Also available are hpet and acpi_pm. > Switching to hpet or acpi_pm does not have visible effect, at > least not while the guest is running. acpi_pm takes more cycles to read. On my laptop switching from hpet to acpi_pm caused the winxp VM to jump up in CPU usage. For both time sources 'perf top -p ' shows timer reads as the top function for qemu-kvm (e.g., read_hpet). On a Nehalem box the clock source is TSC. 'perf top -p ' for a winxp VM does not show clock reads at all. David >=20 > Thanks! >=20 > /mjt