Date: Mon, 1 Dec 2014 15:19:50 +0100
From: Cornelia Huck <cornelia.huck@de.ibm.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>, linux-kernel@vger.kernel.org,
        David Miller <davem@davemloft.net>, rusty@au1.ibm.com,
        nab@linux-iscsi.org, pbonzini@redhat.com, thuth@linux.vnet.ibm.com,
        Rusty Russell <rusty@rustcorp.com.au>,
        virtualization@lists.linux-foundation.org, linux-api@vger.kernel.org
Subject: Re: [PATCH v7 16/46] virtio_blk: v1.0 support
Message-ID: <20141201151950.0df00078.cornelia.huck@de.ibm.com>
In-Reply-To: <20141201134719.GA18305@redhat.com>
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On Mon, 1 Dec 2014 15:47:19 +0200
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Mon, Dec 01, 2014 at 02:00:04PM +0100, Cornelia Huck wrote:
> > On Mon, 1 Dec 2014 14:51:26 +0200
> > "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > 
> > > On Mon, Dec 01, 2014 at 01:40:36PM +0100, Cornelia Huck wrote:
> > > > On Mon, 1 Dec 2014 14:34:55 +0200
> > > > "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > > > 
> > > > > On Mon, Dec 01, 2014 at 01:02:58PM +0100, Cornelia Huck wrote:
> > > > > > On Mon, 1 Dec 2014 13:46:45 +0200
> > > > > > "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > > > > > 
> > > > > > > On Mon, Dec 01, 2014 at 12:33:15PM +0100, Cornelia Huck wrote:
> > > > > > > > On Mon, 1 Dec 2014 11:26:58 +0200
> > > > > > > > "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > > > > > > > 
> > > > > > > > > For some places on data path, it might be worth it
> > > > > > > > > to cache the correct value e.g. as part of device
> > > > > > > > > structure. This replaces a branch with a memory load,
> > > > > > > > > so the gain would have to be measured, best done
> > > > > > > > > separately?
> > > > > > > > 
> > > > > > > > I think we'll want to do some measuring once the basic structure is
> > > > > > > > in place anyway.
> > > > > > > 
> > > > > > > What's meant by in place here?
> > > > > > 
> > > > > > That this patchset is ready :)
> > > > > 
> > > > > Also it's ready to the level where benchmarking is possible, right?  I
> > > > > don't think you should wait until we finish polishing up commit
> > > > > messages.
> > > > 
> > > > My point is that I haven't even found time yet to test this
> > > > thouroughly :(
> > > 
> > > If my experience shows anything, it's unlikely we'll get appropriate
> > > testing without code being upstream first.
> > > That's why I pushed on with sparse tagging btw.
> > > This way we can be reasonably sure we didn't miss some path.
> > 
> > I know that I'm likely the only one to test ccw (unless I manage to get
> > some other also-busy people to try this out).
> > 
> > What's the status of virtio-pci, btw? Can people actually test this
> > sanely?
> 
> Sure, I'm testing that it's not broken by these patches.
> Others can do so, too.

So basically just regression testing, right?

> 
> Once ccw is done on host and guest (will be complete after I
> send v8), it will be easier to add virtio 1.0 for more transports.
> 
> OTOH if we require that everything is ready and perfect before merging
> anything we'll never get anywhere.

I'm not looking for perfect, I'm just trying to juggle testing this +
doing qemu changes + various other stuff that is eating my time :)

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