From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Glauber Costa <glommer@redhat.com>
Cc: kvm@vger.kernel.org, avi@redhat.com, zamsden@redhat.com,
mtosatti@redhat.com, riel@redhat.com, peterz@infradead.org,
mingo@elte.hu
Subject: Re: [RFC v2 6/7] touch softlockup watchdog
Date: Mon, 30 Aug 2010 10:33:26 -0700 [thread overview]
Message-ID: <4C7BEB66.6050301@goop.org> (raw)
In-Reply-To: <1283184391-7785-13-git-send-email-glommer@redhat.com>
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 <glommer@redhat.com>
> ---
> 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);
>
next prev parent reply other threads:[~2010-08-30 17:33 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-30 16:06 [RFC v2 0/7] kvm stael time implementation Glauber Costa
2010-08-30 16:06 ` [RFC v2 1/7] change headers preparing for steal time Glauber Costa
2010-08-30 16:06 ` [RFC 1/8] Implement getnsboottime kernel API Glauber Costa
2010-08-30 16:06 ` [RFC v2 2/7] always call kvm_write_guest Glauber Costa
2010-08-30 16:06 ` [RFC 2/8] change headers preparing for steal time Glauber Costa
2010-08-30 16:06 ` [RFC 3/8] always call kvm_write_guest Glauber Costa
2010-08-30 16:06 ` [RFC v2 3/7] measure time out of guest Glauber Costa
2010-08-30 16:06 ` [RFC v2 4/7] change kernel accounting to include steal time Glauber Costa
2010-08-30 16:06 ` [RFC 4/8] measure time out of guest Glauber Costa
2010-08-30 16:06 ` [RFC 5/8] change kernel accounting to include steal time Glauber Costa
2010-08-30 16:06 ` [RFC v2 5/7] kvm steal time implementation Glauber Costa
2010-08-30 16:06 ` [RFC 6/8] " Glauber Costa
2010-08-30 16:06 ` [RFC v2 6/7] touch softlockup watchdog Glauber Costa
2010-08-30 16:06 ` [RFC v2 7/7] tell guest about steal time feature Glauber Costa
2010-08-30 16:06 ` [RFC 7/8] touch softlockup watchdog Glauber Costa
2010-08-30 16:06 ` [RFC 8/8] tell guest about steal time feature Glauber Costa
2010-08-30 17:33 ` Jeremy Fitzhardinge [this message]
2010-08-30 18:07 ` [RFC v2 6/7] touch softlockup watchdog Glauber Costa
2010-08-30 16:46 ` [RFC 5/8] change kernel accounting to include steal time Peter Zijlstra
2010-08-30 17:26 ` Glauber Costa
2010-08-30 17:30 ` [RFC v2 4/7] " Jeremy Fitzhardinge
2010-08-30 18:39 ` Rik van Riel
2010-08-30 19:07 ` Jeremy Fitzhardinge
2010-08-30 19:14 ` Peter Zijlstra
2010-08-30 19:17 ` Rik van Riel
2010-08-30 19:20 ` Peter Zijlstra
2010-08-30 19:45 ` Rik van Riel
2010-08-30 22:56 ` Jeremy Fitzhardinge
2010-08-30 23:03 ` Rik van Riel
2010-08-31 8:11 ` Peter Zijlstra
2010-09-02 18:19 ` Glauber Costa
2010-09-03 3:24 ` Jeremy Fitzhardinge
2010-09-03 7:18 ` Peter Zijlstra
2010-09-01 23:56 ` [RFC 1/8] Implement getnsboottime kernel API Zachary Amsden
2010-08-30 16:37 ` [RFC v2 0/7] kvm stael time implementation Peter Zijlstra
2010-08-30 16:45 ` Jeremy Fitzhardinge
2010-08-30 17:21 ` Glauber Costa
2010-08-30 17:20 ` Jeremy Fitzhardinge
2010-08-30 17:06 [RFC v2 0/7] kvm steal time implementation proposal Glauber Costa
2010-08-30 17:06 ` [RFC v2 6/7] touch softlockup watchdog Glauber Costa
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