linux-kernel - Re: [PATCH 0/9] RFC: NVME VFIO mediated device

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Message-ID: <e0491452300bca37a716499b6ecd4e9f1c2f8c99.camel@redhat.com>
Date:   Wed, 20 Mar 2019 18:48:17 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Bart Van Assche <bvanassche@....org>,
        linux-nvme@...ts.infradead.org
Cc:     Fam Zheng <fam@...hon.net>, Keith Busch <keith.busch@...el.com>,
        Sagi Grimberg <sagi@...mberg.me>, kvm@...r.kernel.org,
        "David S . Miller" <davem@...emloft.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Liang Cunming <cunming.liang@...el.com>,
        Wolfram Sang <wsa@...-dreams.de>, linux-kernel@...r.kernel.org,
        Kirti Wankhede <kwankhede@...dia.com>,
        Jens Axboe <axboe@...com>,
        Alex Williamson <alex.williamson@...hat.com>,
        John Ferlan <jferlan@...hat.com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Liu Changpeng <changpeng.liu@...el.com>,
        "Paul E . McKenney" <paulmck@...ux.ibm.com>,
        Amnon Ilan <ailan@...hat.com>, Christoph Hellwig <hch@....de>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>
Subject: Re: [PATCH 0/9] RFC: NVME VFIO mediated device

On Wed, 2019-03-20 at 08:08 -0700, Bart Van Assche wrote:
> On Tue, 2019-03-19 at 16:41 +0200, Maxim Levitsky wrote:
> > * Polling kernel thread is used. The polling is stopped after a 
> > predefined timeout (1/2 sec by default).
> > Support for all interrupt driven mode is planned, and it shows promising
> > results.
> 
> Which cgroup will the CPU cycles used for polling be attributed to? Can the
> polling code be moved into user space such that it becomes easy to identify
> which process needs most CPU cycles for polling and such that the polling
> CPU cycles are attributed to the proper cgroup?


Currently there is a single IO thread per each virtual controller instance.
I would prefer to keep all the driver in the kernel, but I think I can make it
cgroup aware, in a simiar way this is done in vhost-net, and vhost-scsi.

Best regards,
	Maxim Levitsky


> Thanks,
> 
> Bart.