linux-kernel - Re: [virtio-dev] Re: [PATCH v2 4/5] virtio-mmio: add MSI interrupt feature support

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Message-ID: <20200212041317-mutt-send-email-mst@kernel.org>
Date:   Wed, 12 Feb 2020 04:15:01 -0500
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     virtio-dev@...ts.oasis-open.org,
        Zha Bin <zhabin@...ux.alibaba.com>, slp@...hat.com,
        "Liu, Jing2" <jing2.liu@...ux.intel.com>,
        linux-kernel@...r.kernel.org, qemu-devel@...gnu.org,
        chao.p.peng@...ux.intel.com, gerry@...ux.alibaba.com
Subject: Re: [virtio-dev] Re: [PATCH v2 4/5] virtio-mmio: add MSI interrupt
 feature support

On Wed, Feb 12, 2020 at 05:03:00PM +0800, Jason Wang wrote:
> 
> On 2020/2/11 下午10:00, Michael S. Tsirkin wrote:
> > > Yes, it can work but it may bring extra effort when you want to mask a
> > > vector which is was shared by a lot of queues.
> > > 
> > > Thanks
> > > 
> > masking should be per vq too.
> > 
> > -- 
> 
> 
> Yes, but if the vector is shard by e.g 16 queues, then all those virtqueues
> needs to be masked which is expensive.
> 
> Thanks

I think that's ok - masking is rare. in fact if vectors can be
changed atomically I'm no longer sure they are needed,
maybe a destructive "disable" which can lose interrupts
is enough.

-- 
MST