Message-ID: <1447184258.31884.91.camel@kernel.crashing.org>
Subject: Re: [PATCH v4 0/6] virtio core DMA API conversion
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>, Andy Lutomirski <luto@kernel.org>,
        David Woodhouse <dwmw2@infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "David S. Miller" <davem@davemloft.net>, sparclinux@vger.kernel.org,
        Joerg Roedel <jroedel@suse.de>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Cornelia Huck <cornelia.huck@de.ibm.com>,
        Sebastian Ott <sebott@linux.vnet.ibm.com>,
        Paolo Bonzini <pbonzini@redhat.com>, Christoph Hellwig <hch@lst.de>,
        KVM <kvm@vger.kernel.org>, Martin Schwidefsky <schwidefsky@de.ibm.com>,
        linux-s390 <linux-s390@vger.kernel.org>,
        Linux Virtualization <virtualization@lists.linux-foundation.org>
Date: Wed, 11 Nov 2015 06:37:38 +1100
In-Reply-To: <20151110142633-mutt-send-email-mst@redhat.com>
References: <cover.1446162273.git.luto@kernel.org>
	 <20151109133624-mutt-send-email-mst@redhat.com>
	 <1447109937.31884.42.camel@kernel.crashing.org>
	 <CALCETrX7Gkw3WrBHff=TpCFHj444E8hHcR6sAqOghQFBo5wp_A@mail.gmail.com>
	 <1447121076.31884.61.camel@kernel.crashing.org>
	 <CALCETrW5_bKCX5gKYaH5y4rvD9jrjY5O5d=oX8hHtAM9EE2Bew@mail.gmail.com>
	 <1447133316.31884.67.camel@kernel.crashing.org>
	 <CALCETrVPQc04Ah7FXcRMb4RhpUJ1WPCoC_4dbacB8a+u5XpmwA@mail.gmail.com>
	 <1447151874.31884.82.camel@kernel.crashing.org>
	 <20151110142633-mutt-send-email-mst@redhat.com>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 639
Lines: 17

On Tue, 2015-11-10 at 14:43 +0200, Michael S. Tsirkin wrote:
> But not virtio-pci I think - that's broken for that usecase since we use
> weaker barriers than required for real IO, as these have measureable
> overhead.  We could have a feature "is a real PCI device",
> that's completely reasonable.

Do we use weaker barriers on the Linux driver side ? I didn't think so
... 

Cheers,
Ben.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/