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From: Wanpeng Li <wanpeng.li@linux.intel.com>
To: Andrew Honig <ahonig@google.com>
Cc: "Wu, Feng" <feng.wu@intel.com>,
	Steve Rutherford <srutherford@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [RFC PATCH 1/4] KVM: x86: Split the APIC from the rest of IRQCHIP.
Date: Fri, 15 May 2015 13:03:02 +0800	[thread overview]
Message-ID: <20150515050302.GA7255@kernel> (raw)
In-Reply-To: <CAKB9nXuzkeYZAiyTcvu=QgqN9TQB0kCr3-8CAvkREN-7Z=ieNw@mail.gmail.com>

On Thu, May 14, 2015 at 12:29:21PM -0700, Andrew Honig wrote:
>>
>> BTW, what is the purpose of this series. If I understand it correctly, you only want to
>> use the in-kernel lapic and leave the others (pic, ioapic) in userspace, what is the
>> benefit of it?
>
>The purpose is to achieve the security benefit of removing some of the
>interrupt handling into userspace, without incurring a significant
>performance penalty.  If you move the entire IRQCHIP into userspace,
>we've seen perf impacts from 15-200% depending on the workload.  With
>this patch series, we're seeing perf penalty <1% on our tests (TCP_RR

Why keep pic and ioapic in kernel space not get obvious benefit, what's
the bottleneck?

Regards,
Wanpeng Li 

>latency, TCP throughput, and Disk I/O).  See
>(https://lwn.net/Articles/619332/)
>
>>
>> Thanks,
>> Feng
>>
>>>
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  parent reply	other threads:[~2015-05-15  5:20 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-13  1:47 [RFC PATCH 1/4] KVM: x86: Split the APIC from the rest of IRQCHIP Steve Rutherford
2015-05-13  1:47 ` [RFC PATCH 2/4] KVM: x86: Add KVM exit for IOAPIC EOIs Steve Rutherford
2015-05-13  7:35   ` Paolo Bonzini
2015-05-13 22:18     ` Steve Rutherford
2015-05-24 16:46   ` Avi Kivity
2015-05-27  2:06     ` Steve Rutherford
2015-05-27  5:32       ` Avi Kivity
2015-05-28 21:58         ` Steve Rutherford
2015-05-13  1:47 ` [RFC PATCH 3/4] KVM: x86: Add EOI exit bitmap inference Steve Rutherford
2015-05-13  6:12   ` Jan Kiszka
2015-05-13  8:04     ` Paolo Bonzini
2015-05-13  8:10       ` Jan Kiszka
2015-05-13  9:24         ` Paolo Bonzini
2015-05-13 10:25           ` Jan Kiszka
2015-05-13 13:04             ` Paolo Bonzini
2015-05-13 13:19               ` Jan Kiszka
2015-05-13 22:21       ` Steve Rutherford
2015-05-15  2:38       ` Steve Rutherford
2015-05-13  7:51   ` Paolo Bonzini
2015-05-13 22:24     ` Steve Rutherford
2015-05-14  9:20       ` Paolo Bonzini
2015-05-14 15:23         ` Alex Williamson
2015-05-14 15:46           ` Paolo Bonzini
2015-05-14 16:04             ` Alex Williamson
2015-05-14 22:10               ` Steve Rutherford
2015-05-14 22:35                 ` Alex Williamson
2015-05-14 23:21                   ` Steve Rutherford
2015-05-13  1:47 ` [RFC PATCH 4/4] KVM: x86: Add support for local interrupt requests from userspace Steve Rutherford
2015-05-13  6:12   ` Jan Kiszka
2015-05-13 22:41     ` Steve Rutherford
2015-05-15 13:27       ` Jan Kiszka
2015-05-13  7:22   ` Paolo Bonzini
2015-05-13 23:13     ` Steve Rutherford
2015-05-13  7:57 ` [RFC PATCH 1/4] KVM: x86: Split the APIC from the rest of IRQCHIP Paolo Bonzini
2015-05-13 22:10   ` Steve Rutherford
2015-05-14  9:12     ` Wu, Feng
2015-05-14 19:29       ` Andrew Honig
2015-05-15  1:28         ` Wu, Feng
2015-05-15  5:03         ` Wanpeng Li [this message]
2015-05-15 18:10           ` Steve Rutherford
2015-05-18  2:11             ` Wanpeng Li

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