From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>
Cc: joelaf@google.com, linux-kernel@vger.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
suleiman@google.com, kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC][PATCH 0/4] arm64:kvm: teach guest sched that VCPUs can be preempted
Date: Mon, 17 Aug 2020 11:03:10 +0900 [thread overview]
Message-ID: <20200817020310.GA1210848@jagdpanzerIV.localdomain> (raw)
In-Reply-To: <20200721041742.197354-1-sergey.senozhatsky@gmail.com>
On (20/07/21 13:17), Sergey Senozhatsky wrote:
> Hello,
>
> RFC
>
> We noticed that in a number of cases when we wake_up_process()
> on arm64 guest we end up enqueuing that task on a preempted VCPU. The culprit
> appears to be the fact that arm64 guests are not aware of VCPU preemption
> as such, so when sched picks up an idle VCPU it always assumes that VCPU
> is available:
>
> wake_up_process()
> try_to_wake_up()
> select_task_rq_fair()
> available_idle_cpu()
> vcpu_is_preempted() // return false;
>
> Which is, obviously, not the case.
>
> This RFC patch set adds a simple vcpu_is_preempted() implementation so
> that scheduler can make better decisions when it search for the idle
> (v)CPU.
Hi,
A gentle ping.
-ss
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next prev parent reply other threads:[~2020-08-17 7:55 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-21 4:17 [RFC][PATCH 0/4] arm64:kvm: teach guest sched that VCPUs can be preempted Sergey Senozhatsky
2020-07-21 4:17 ` [RFC][PATCH 1/4] arm64:kvm: define pv_state SMCCC HV calls Sergey Senozhatsky
2020-07-21 4:17 ` [RFC][PATCH 2/4] arm64: add guest pvstate support Sergey Senozhatsky
2020-07-21 4:17 ` [RFC][PATCH 3/4] arm64: add host " Sergey Senozhatsky
2020-07-21 4:17 ` [RFC][PATCH 4/4] arm64: do not use dummy vcpu_is_preempted() anymore Sergey Senozhatsky
2020-08-17 2:03 ` Sergey Senozhatsky [this message]
2020-08-17 12:03 ` [RFC][PATCH 0/4] arm64:kvm: teach guest sched that VCPUs can be preempted yezengruan
2020-08-17 12:25 ` Marc Zyngier
2020-08-17 14:15 ` yezengruan
2020-09-11 8:58 ` Sergey Senozhatsky
2020-12-08 20:02 ` Joel Fernandes
2020-12-09 9:43 ` Marc Zyngier
2020-12-10 1:39 ` Joel Fernandes
2020-12-10 8:45 ` Marc Zyngier
2020-12-11 9:34 ` Quentin Perret
2020-12-16 1:45 ` Joel Fernandes
2020-09-11 8:46 ` Sergey Senozhatsky
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