From: Yang Zhang <yang.zhang.wz@gmail.com>
To: Nadav Amit <nadav.amit@gmail.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>,
"Jan Kiszka" <jan.kiszka@siemens.com>,
"Lan, Tianyu" <tianyu.lan@intel.com>,
pbonzini@redhat.com, kvm@vger.kernel.org, tglx@linutronix.de,
gleb@redhat.com, mst@redhat.com, x86@kernel.org,
"Peter Xu" <peterx@redhat.com>,
"Igor Mammedov" <imammedo@redhat.com>
Subject: Re: Enable more than 255 VCPU support without irq remapping function in the guest
Date: Tue, 3 May 2016 09:34:31 +0800 [thread overview]
Message-ID: <57280027.4020005@gmail.com> (raw)
In-Reply-To: <6818B0B0-6F29-494D-8EA9-D69603AF6ED6@gmail.com>
On 2016/4/29 11:01, Nadav Amit wrote:
> Yang Zhang <yang.zhang.wz@gmail.com> wrote:
>
>> On 2016/4/28 23:32, Radim Krčmář wrote:
>>> I think we are talking about extending KVM's IR-less x2APIC, when
>>> standard x2APIC is the future.
>>
>> Yes, Since IR is only useful for the external device, and 255 CPUs is enough to handle the interrupts from external devices. Besides, i think virtual VT-d will bring extra performance impaction for devices, so if IR-less X2APIC also works well with more than 255 VCPUs, maybe extending KVM with IR-less x2apic is not a bad idea.
>
> So will you use x2APIC physical mode in this system?
Probably, cluster mode is the better choice.
> Try not to send a multicast IPI to 400 cores in the VM...
Yes, a multicast IPI to so many cores is a disaster in VM, like
flush_tlb_others().
--
best regards
yang
next prev parent reply other threads:[~2016-05-03 1:34 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-26 16:14 Enable more than 255 VCPU support without irq remapping function in the guest Lan, Tianyu
2016-04-26 16:17 ` Jan Kiszka
2016-04-26 16:49 ` Radim Krčmář
2016-04-27 4:10 ` Yang Zhang
2016-04-27 5:24 ` Jan Kiszka
2016-04-27 6:24 ` Lan Tianyu
2016-04-27 6:56 ` Jan Kiszka
2016-04-27 9:39 ` Yang Zhang
2016-04-27 9:45 ` Jan Kiszka
2016-04-28 1:11 ` Yang Zhang
2016-04-28 6:54 ` Jan Kiszka
2016-04-28 15:32 ` Radim Krčmář
2016-04-29 2:09 ` Yang Zhang
2016-04-29 3:01 ` Nadav Amit
2016-05-03 1:34 ` Yang Zhang [this message]
2016-04-29 4:59 ` Jan Kiszka
2016-05-03 1:52 ` Yang Zhang
2016-05-03 2:03 ` Nadav Amit
2016-05-03 4:55 ` Jan Kiszka
2016-05-04 1:46 ` Yang Zhang
2016-05-04 1:56 ` Nadav Amit
2016-05-04 5:38 ` Jan Kiszka
2016-04-27 5:39 ` Lan Tianyu
2016-04-27 14:38 ` Radim Krčmář
2016-04-27 5:15 ` Lan Tianyu
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