From: Sean Christopherson <seanjc@google.com>
To: Haiwei Li <lihaiwei.kernel@gmail.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
pbonzini@redhat.com, vkuznets@redhat.com, wanpengli@tencent.com,
jmattson@google.com, joro@8bytes.org,
Haiwei Li <lihaiwei@tencent.com>
Subject: Re: [PATCH] kvm: lapic: add module parameters for LAPIC_TIMER_ADVANCE_ADJUST_MAX/MIN
Date: Tue, 9 Mar 2021 15:42:15 -0800 [thread overview]
Message-ID: <YEgH11nNwdCkF5kT@google.com> (raw)
In-Reply-To: <03239d81-df56-a6c9-c79d-c14d22f62705@gmail.com>
On Wed, Mar 03, 2021, Haiwei Li wrote:
> On 21/3/3 10:09, lihaiwei.kernel@gmail.com wrote:
> > From: Haiwei Li <lihaiwei@tencent.com>
> >
> > In my test environment, advance_expire_delta is frequently greater than
> > the fixed LAPIC_TIMER_ADVANCE_ADJUST_MAX. And this will hinder the
> > adjustment.
>
> Supplementary details:
>
> I have tried to backport timer related features to our production
> kernel.
>
> After completed, i found that advance_expire_delta is frequently greater
> than the fixed value. It's necessary to trun the fixed to dynamically
> values.
Does this reproduce on an upstream kernel? If so...
1. How much over the 10k cycle limit is the delta?
2. Any idea what causes the large delta? E.g. is there something that can
and/or should be fixed elsewhere?
3. Is it platform/CPU specific?
Ideally, KVM would play nice with "all" environments by default without forcing
the admin to hand-tune things.
next prev parent reply other threads:[~2021-03-09 23:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-03 2:09 [PATCH] kvm: lapic: add module parameters for LAPIC_TIMER_ADVANCE_ADJUST_MAX/MIN lihaiwei.kernel
2021-03-03 2:39 ` Haiwei Li
2021-03-09 23:42 ` Sean Christopherson [this message]
2021-03-10 9:15 ` Haiwei Li
2021-03-13 0:58 ` Sean Christopherson
2021-03-13 1:31 ` Haiwei Li
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