Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 11 Aug 2021 09:31:21 +0000
From:   Floris Westermann <westermann@google.com>
To:     Cristian Marussi <cristian.marussi@arm.com>
Cc:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        virtualization@lists.linux-foundation.org,
        virtio-dev@lists.oasis-open.org, sudeep.holla@arm.com,
        james.quinlan@broadcom.com, Jonathan.Cameron@huawei.com,
        f.fainelli@gmail.com, etienne.carriere@linaro.org,
        vincent.guittot@linaro.org, souvik.chakravarty@arm.com,
        igor.skalkin@opensynergy.com, peter.hilber@opensynergy.com,
        alex.bennee@linaro.org, jean-philippe@linaro.org,
        mikhail.golubev@opensynergy.com, anton.yakovlev@opensynergy.com,
        Vasyl.Vavrychuk@opensynergy.com,
        Andriy.Tryshnivskyy@opensynergy.com
Subject: Re: [PATCH v6 00/17] Introduce SCMI transport based on VirtIO
Message-ID: <YROY6YntswWxfaub@google.com>
References: <20210712141833.6628-1-cristian.marussi@arm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20210712141833.6628-1-cristian.marussi@arm.com>
Precedence: bulk

Hi Cristian,

I am currently working on an interface for VMs to communicate their
performance requirements to the hosts by passing through cpu frequency
adjustments.

Your patch looks very interesting but I have some questions:


On Mon, Jul 12, 2021 at 03:18:16PM +0100, Cristian Marussi wrote:
>
> The series has been tested using an emulated fake SCMI device and also a
> proper SCP-fw stack running through QEMU vhost-users, with the SCMI stack
> compiled, in both cases, as builtin and as a loadable module, running tests
> against mocked SCMI Sensors using HWMON and IIO interfaces to check the
> functionality of notifications and sync/async commands.
>
> Virtio-scmi support has been exercised in the following testing scenario
> on a JUNO board:
>
>  - normal sync/async command transfers
>  - notifications
>  - concurrent delivery of correlated response and delayed responses
>  - out-of-order delivery of delayed responses before related responses
>  - unexpected delayed response delivery for sync commands
>  - late delivery of timed-out responses and delayed responses
>
> Some basic regression testing against mailbox transport has been performed
> for commands and notifications too.
>
> No sensible overhead in total handling time of commands and notifications
> has been observed, even though this series do indeed add a considerable
> amount of code to execute on TX path.
> More test and measurements could be needed in these regards.
>

Can you share any data and benchmarks using you fake SCMI device.
Also, could you provide the emulated device code so that the results can
be reproduced.


Cheers,
Floris