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From: Paolo Bonzini <pbonzini@redhat.com>
To: yunhong jiang <yunhong.jiang@linux.intel.com>,
	David Matlack <dmatlack@google.com>
Cc: "kvm list" <kvm@vger.kernel.org>,
	"Marcelo Tosatti" <mtosatti@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Wanpeng Li" <kernellwp@gmail.com>
Subject: Re: [RFC PATCH V2 4/4] Utilize the vmx preemption timer for tsc deadline timer
Date: Wed, 25 May 2016 13:58:17 +0200	[thread overview]
Message-ID: <e74fa15b-c684-3b63-48eb-4c053668b94c@redhat.com> (raw)
In-Reply-To: <20160524163556.462c3309@jnakajim-build>



On 25/05/2016 01:35, yunhong jiang wrote:
>> > Does this interact correctly with TSC scaling? IIUC this programs the
>> > VMX preemption timer with a delay in guest cycles, rather than host
>> > cycles.
> Aha, good point, thanks!
> 
> But I re-checked the lapic.c and seems this issue has never been considered?
> Check http://lxr.free-electrons.com/source/arch/x86/kvm/lapic.c#L1335 

This is a bug indeed.  The simplest fix would be to ignore
lapic_timer_advance_ns when TSC scaling is in use.

> and lxr.free-electrons.com/source/arch/x86/kvm/lapic.c#L1335

You copied the wrong URL, but at least lines 1383-1410 seem okay to me.

> for example. Also I
> tried to find a function to translate guest tsc to host tsc and didn't find
> such function at all.

See my other reply.

Thanks,

Paolo

  reply	other threads:[~2016-05-25 11:58 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-24 22:27 [RFC PATCH V2 0/4] Utilizing VMX preemption for timer virtualization Yunhong Jiang
2016-05-24 22:27 ` [RFC PATCH V2 1/4] Add the kvm sched_out hook Yunhong Jiang
2016-05-24 22:27 ` [RFC PATCH V2 2/4] Utilize the vmx preemption timer Yunhong Jiang
2016-06-14 13:23   ` Roman Kagan
2016-06-14 13:41     ` Paolo Bonzini
2016-06-14 16:46       ` yunhong jiang
2016-06-14 21:56         ` Paolo Bonzini
2016-06-15 18:03           ` yunhong jiang
2016-06-14 16:46     ` yunhong jiang
2016-05-24 22:27 ` [RFC PATCH V2 3/4] Separate the start_sw_tscdeadline Yunhong Jiang
2016-05-24 22:27 ` [RFC PATCH V2 4/4] Utilize the vmx preemption timer for tsc deadline timer Yunhong Jiang
2016-05-24 23:11   ` David Matlack
2016-05-24 23:35     ` yunhong jiang
2016-05-25 11:58       ` Paolo Bonzini [this message]
2016-05-25 22:53         ` yunhong jiang
2016-05-26  7:20           ` Paolo Bonzini
2016-05-25 10:40     ` Paolo Bonzini
2016-05-25 13:38       ` Radim Krčmář
2016-05-25 11:52   ` Paolo Bonzini
2016-05-25 22:44     ` yunhong jiang
2016-05-26 14:05       ` Alan Jenkins
2016-05-26 15:32         ` Paolo Bonzini
2016-06-04  0:24     ` yunhong jiang
2016-06-06 13:49       ` Paolo Bonzini
2016-06-06 18:21         ` yunhong jiang
2016-05-25 13:27   ` Radim Krčmář
2016-05-25 13:51     ` Paolo Bonzini
2016-05-25 14:31       ` Radim Krčmář
2016-05-25 23:13         ` yunhong jiang
2016-06-14 11:34         ` Paolo Bonzini
2016-05-25 13:45   ` Radim Krčmář
2016-05-25 22:57     ` yunhong jiang

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