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From: "Gonglei (Arei)" <arei.gonglei@huawei.com>
To: "Michael S. Tsirkin" <mst@redhat.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	"virtio-dev@lists.oasis-open.org"
	<virtio-dev@lists.oasis-open.org>,
	"virtualization@lists.linux-foundation.org"
	<virtualization@lists.linux-foundation.org>,
	"linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"herbert@gondor.apana.org.au" <herbert@gondor.apana.org.au>,
	"Huangweidong (C)" <weidong.huang@huawei.com>,
	Claudio Fontana <Claudio.Fontana@huawei.com>,
	Luonengjun <luonengjun@huawei.com>,
	"Hanweidong (Randy)" <hanweidong@huawei.com>,
	"Xuquan (Quan Xu)" <xuquan8@huawei.com>,
	"Wanzongshun (Vincent)" <wanzongshun@huawei.com>,
	"stefanha@redhat.com" <stefanha@redhat.com>,
	"Zhoujian (jay, Euler)" <
Subject: RE: [PATCH v8 1/1] crypto: add virtio-crypto driver
Date: Fri, 13 Jan 2017 01:56:03 +0000	[thread overview]
Message-ID: <33183CC9F5247A488A2544077AF19020DA18F954@DGGEMA505-MBX.china.huawei.com> (raw)
In-Reply-To: <20170112161729-mutt-send-email-mst@kernel.org>

> 
> On Thu, Jan 12, 2017 at 03:10:25PM +0100, Christian Borntraeger wrote:
> > On 01/10/2017 01:56 PM, Christian Borntraeger wrote:
> > > On 01/10/2017 01:36 PM, Gonglei (Arei) wrote:
> > >> Hi,
> > >>
> > >>>
> > >>> On 12/15/2016 03:03 AM, Gonglei wrote:
> > >>> [...]
> > >>>> +
> > >>>> +static struct crypto_alg virtio_crypto_algs[] = { {
> > >>>> +	.cra_name = "cbc(aes)",
> > >>>> +	.cra_driver_name = "virtio_crypto_aes_cbc",
> > >>>> +	.cra_priority = 501,
> > >>>
> > >>>
> > >>> This is still higher than the hardware-accelerators (like intel aesni or the
> > >>> s390 cpacf functions or the arm hw). aesni and s390/cpacf are supported
> by the
> > >>> hardware virtualization and available to the guests. I do not see a way
> how
> > >>> virtio
> > >>> crypto can be faster than that (in the end it might be cpacf/aesni +
> overhead)
> > >>> instead it will very likely be slower.
> > >>> So we should use a number that is higher than software implementations
> but
> > >>> lower than the hw ones.
> > >>>
> > >>> Just grepping around, the software ones seem be be around 100 and the
> > >>> hardware
> > >>> ones around 200-400. So why was 150 not enough?
> > >>>
> > >> I didn't find a documentation about how we use the priority, and I assumed
> > >> people use virtio-crypto will configure hardware accelerators in the
> > >> host. So I choosed the number which bigger than aesni's priority.
> > >
> > > Yes, but the aesni driver will only bind if there is HW support in the guest.
> > > And if aesni is available in the guest (or the s390 aes function from cpacf)
> > > it will always be faster than the same in the host via virtio.So your priority
> > > should be smaller.
> >
> >
> > any opinion on this?
> 
> Going forward, we might add an emulated aesni device and that might
> become slower than virtio. OTOH if or when this happens, we can solve it
> by adding a priority or a feature flag to virtio to raise its priority.
> 
> So I think I agree with Christian here, let's lower the priority.
> Gonglei, could you send a patch like this?
> 
OK, will do.

Thanks,
-Gonglei

      reply	other threads:[~2017-01-13  1:58 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-15  2:03 [PATCH v8 0/1] virtio-crypto: add Linux driver Gonglei
2016-12-15  2:03 ` [PATCH v8 1/1] crypto: add virtio-crypto driver Gonglei
2017-01-10 12:27   ` Christian Borntraeger
2017-01-10 12:36     ` Gonglei (Arei)
2017-01-10 12:56       ` Christian Borntraeger
2017-01-12 14:10         ` Christian Borntraeger
2017-01-12 14:23           ` Michael S. Tsirkin
2017-01-13  1:56             ` Gonglei (Arei) [this message]

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