From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [RFC v2 6/7] touch softlockup watchdog Date: Mon, 30 Aug 2010 10:33:26 -0700 Message-ID: <4C7BEB66.6050301@goop.org> References: <1283184391-7785-1-git-send-email-glommer@redhat.com> <1283184391-7785-2-git-send-email-glommer@redhat.com> <1283184391-7785-3-git-send-email-glommer@redhat.com> <1283184391-7785-4-git-send-email-glommer@redhat.com> <1283184391-7785-5-git-send-email-glommer@redhat.com> <1283184391-7785-6-git-send-email-glommer@redhat.com> <1283184391-7785-7-git-send-email-glommer@redhat.com> <1283184391-7785-8-git-send-email-glommer@redhat.com> <1283184391-7785-9-git-send-email-glommer@redhat.com> <1283184391-7785-10-git-send-email-glommer@redhat.com> <1283184391-7785-11-git-send-email-glommer@redhat.com> <1283184391-7785-12-git-send-email-glommer@redhat.com> <1283184391-7785-13-git-send-email-glommer@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, avi@redhat.com, zamsden@redhat.com, mtosatti@redhat.com, riel@redhat.com, peterz@infradead.org, mingo@elte.hu To: Glauber Costa Return-path: Received: from claw.goop.org ([74.207.240.146]:46577 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751733Ab0H3Rda (ORCPT ); Mon, 30 Aug 2010 13:33:30 -0400 In-Reply-To: <1283184391-7785-13-git-send-email-glommer@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/30/2010 09:06 AM, Glauber Costa wrote: > With a reliable steal time mechanism, we can tell if we're > out of the cpu for very long, differentiating from the case > that we simply got a real softlockup. > > In the case we were out of cpu, the watchdog is fed, making > bogus softlockups disappear. Why not change the softlockup to measure unstolen time rather than explicitly poking it from a hypervisor-specific function? How is touching it in kvm_get_steal_time() correct anyway? J > Signed-off-by: Glauber Costa > --- > arch/x86/kernel/kvmclock.c | 5 +++++ > 1 files changed, 5 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c > index a1f4852..d217475 100644 > --- a/arch/x86/kernel/kvmclock.c > +++ b/arch/x86/kernel/kvmclock.c > @@ -91,6 +91,7 @@ cputime_t kvm_get_steal_time(void) > { > u64 delta = 0; > u64 *last_steal_info, this_steal_info; > + int touch_wd; > struct pvclock_vcpu_time_info *src; > > src = &get_cpu_var(hv_clock); > @@ -104,6 +105,10 @@ cputime_t kvm_get_steal_time(void) > > delta = this_steal_info - *last_steal_info; > > + touch_wd = softlockup_thresh * 1000UL; > + if ((touch_wd > 0) && (delta > touch_wd)) > + touch_softlockup_watchdog(); > + > *last_steal_info = this_steal_info; > put_cpu_var(steal_info); >