From: Jon Masters <jcm@redhat.com>
To: speck@linutronix.de
Subject: [MODERATED] Re: Interrupts policy for SMT
Date: Wed, 11 Jul 2018 10:31:59 -0400 [thread overview]
Message-ID: <a2186828-f463-92fe-9222-88e5b0c9df57@redhat.com> (raw)
In-Reply-To: <7a1e2f79-7616-5542-6ccc-32dfcdfc981d@redhat.com>
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On 07/06/2018 02:56 PM, speck for Jon Masters wrote:
> On 07/05/2018 07:07 PM, speck for Andi Kleen wrote:
>
>> 2. Explicitly force the sibling to exit for interrupts
>>
>> The basic idea is to maintain the "i am in a guest" and "i am in
>> an interrupt states in two cache lins.
>> The sibling always checks it before executing interrupts. If
>> is set it sends an IPI. KVM also needs to check and wait
>> for interrupts before entering the guest.
>
> So guest A receives an interrupt, notices that an IPI needs to be sent
> and interrupts sibling thread B. Then B waits until some later time
> before re-entering its guest at the same time as A? How do you do the
> lock-step entry? Do you send a second IPI or spin on some lock value
> that's in this shared cache line you talk about?
>
> Can you provide a worked example?
Andi?
--
Computer Architect | Sent from my Fedora powered laptop
prev parent reply other threads:[~2018-07-11 14:32 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-05 23:07 [MODERATED] Interrupts policy for SMT Andi Kleen
2018-07-06 12:35 ` [MODERATED] " Paolo Bonzini
2018-07-06 16:46 ` Andi Kleen
2018-07-06 17:13 ` Paolo Bonzini
2018-07-06 18:07 ` Andi Kleen
2018-07-06 18:52 ` Jon Masters
2018-07-06 18:56 ` Jon Masters
2018-07-11 14:31 ` Jon Masters [this message]
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