diff mbox

[dpdk-dev,4/5] virtio: fix ring size negotiation

Message ID 1429111219-8789-5-git-send-email-stephen@networkplumber.org (mailing list archive)
State Superseded, archived
Headers

Commit Message

Stephen Hemminger April 15, 2015, 3:20 p.m. UTC 
  This fixes another of the issues with running virtio on non-KVM
envirionments. For example, Google Compute Engine reports a
ring size of 16K.

If guest virtio requests more slots than available then
the queue should just be initialized to the smaller value.

Conversely, if the number of descriptors requested exceeds the virtio
host queue size, then just silently use the smaller host size.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 lib/librte_pmd_virtio/virtio_ethdev.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

Comments

Ouyang Changchun April 16, 2015, 3:39 a.m. UTC | #1 
> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Stephen
> Hemminger
> Sent: Wednesday, April 15, 2015 11:20 PM
> To: dev@dpdk.org
> Subject: [dpdk-dev] [PATCH 4/5] virtio: fix ring size negotiation
> 
> This fixes another of the issues with running virtio on non-KVM
> envirionments. For example, Google Compute Engine reports a ring size of
> 16K.
> 
> If guest virtio requests more slots than available then the queue should just

I suspect 'more' here should be 'less'?

> be initialized to the smaller value.
> 
> Conversely, if the number of descriptors requested exceeds the virtio host
> queue size, then just silently use the smaller host size.
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
>  lib/librte_pmd_virtio/virtio_ethdev.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/librte_pmd_virtio/virtio_ethdev.c
> b/lib/librte_pmd_virtio/virtio_ethdev.c
> index 3cb9c6a..db0232e 100644
> --- a/lib/librte_pmd_virtio/virtio_ethdev.c
> +++ b/lib/librte_pmd_virtio/virtio_ethdev.c
> @@ -267,13 +267,21 @@ int virtio_dev_queue_setup(struct rte_eth_dev
> *dev,
>  	if (vq_size == 0) {
>  		PMD_INIT_LOG(ERR, "%s: virtqueue does not exist",
> __func__);
>  		return -EINVAL;
> -	} else if (!rte_is_power_of_2(vq_size)) {
> +	}
> +
> +	if (!rte_is_power_of_2(vq_size)) {
>  		PMD_INIT_LOG(ERR, "%s: virtqueue size is not powerof 2",
> __func__);
>  		return -EINVAL;
> -	} else if (nb_desc != vq_size) {
> -		PMD_INIT_LOG(ERR, "Warning: nb_desc(%d) is not equal to
> vq size (%d), fall to vq size",
> -			nb_desc, vq_size);
> -		nb_desc = vq_size;
> +	}
> +
> +	if (nb_desc < vq_size) {
> +		if (!rte_is_power_of_2(nb_desc)) {
> +			PMD_INIT_LOG(ERR,
> +				     "nb_desc(%u) size is not powerof 2",
> +				     nb_desc);
> +			return -EINVAL;
> +		}
> +		vq_size = nb_desc;

Don't we need a warning when nb_desc > vq_size?

>  	}
> 
>  	if (queue_type == VTNET_RQ) {
> --
> 2.1.4
Stephen Hemminger April 16, 2015, 5:47 a.m. UTC | #2 
No warning is needed, it just works.

On Wed, Apr 15, 2015 at 8:39 PM, Ouyang, Changchun <
changchun.ouyang@intel.com> wrote:

>
>
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Stephen
> > Hemminger
> > Sent: Wednesday, April 15, 2015 11:20 PM
> > To: dev@dpdk.org
> > Subject: [dpdk-dev] [PATCH 4/5] virtio: fix ring size negotiation
> >
> > This fixes another of the issues with running virtio on non-KVM
> > envirionments. For example, Google Compute Engine reports a ring size of
> > 16K.
> >
> > If guest virtio requests more slots than available then the queue should
> just
>
> I suspect 'more' here should be 'less'?
>
> > be initialized to the smaller value.
> >
> > Conversely, if the number of descriptors requested exceeds the virtio
> host
> > queue size, then just silently use the smaller host size.
> >
> > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> > ---
> >  lib/librte_pmd_virtio/virtio_ethdev.c | 18 +++++++++++++-----
> >  1 file changed, 13 insertions(+), 5 deletions(-)
> >
> > diff --git a/lib/librte_pmd_virtio/virtio_ethdev.c
> > b/lib/librte_pmd_virtio/virtio_ethdev.c
> > index 3cb9c6a..db0232e 100644
> > --- a/lib/librte_pmd_virtio/virtio_ethdev.c
> > +++ b/lib/librte_pmd_virtio/virtio_ethdev.c
> > @@ -267,13 +267,21 @@ int virtio_dev_queue_setup(struct rte_eth_dev
> > *dev,
> >       if (vq_size == 0) {
> >               PMD_INIT_LOG(ERR, "%s: virtqueue does not exist",
> > __func__);
> >               return -EINVAL;
> > -     } else if (!rte_is_power_of_2(vq_size)) {
> > +     }
> > +
> > +     if (!rte_is_power_of_2(vq_size)) {
> >               PMD_INIT_LOG(ERR, "%s: virtqueue size is not powerof 2",
> > __func__);
> >               return -EINVAL;
> > -     } else if (nb_desc != vq_size) {
> > -             PMD_INIT_LOG(ERR, "Warning: nb_desc(%d) is not equal to
> > vq size (%d), fall to vq size",
> > -                     nb_desc, vq_size);
> > -             nb_desc = vq_size;
> > +     }
> > +
> > +     if (nb_desc < vq_size) {
> > +             if (!rte_is_power_of_2(nb_desc)) {
> > +                     PMD_INIT_LOG(ERR,
> > +                                  "nb_desc(%u) size is not powerof 2",
> > +                                  nb_desc);
> > +                     return -EINVAL;
> > +             }
> > +             vq_size = nb_desc;
>
> Don't we need a warning when nb_desc > vq_size?
>
> >       }
> >
> >       if (queue_type == VTNET_RQ) {
> > --
> > 2.1.4
>
>
Ouyang Changchun April 16, 2015, 6:26 a.m. UTC | #3 
From: Stephen Hemminger [mailto:stephen@networkplumber.org]

Sent: Thursday, April 16, 2015 1:48 PM
To: Ouyang, Changchun
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH 4/5] virtio: fix ring size negotiation

No warning is needed, it just works.

I know it works, but the upper user don’t know the descriptor number is reduced.
I concern it is not so user-friendly here.


On Wed, Apr 15, 2015 at 8:39 PM, Ouyang, Changchun <changchun.ouyang@intel.com<mailto:changchun.ouyang@intel.com>> wrote:


> -----Original Message-----

> From: dev [mailto:dev-bounces@dpdk.org<mailto:dev-bounces@dpdk.org>] On Behalf Of Stephen

> Hemminger

> Sent: Wednesday, April 15, 2015 11:20 PM

> To: dev@dpdk.org<mailto:dev@dpdk.org>

> Subject: [dpdk-dev] [PATCH 4/5] virtio: fix ring size negotiation

>

> This fixes another of the issues with running virtio on non-KVM

> envirionments. For example, Google Compute Engine reports a ring size of

> 16K.

>

> If guest virtio requests more slots than available then the queue should just


I suspect 'more' here should be 'less'?

> be initialized to the smaller value.

>

> Conversely, if the number of descriptors requested exceeds the virtio host

> queue size, then just silently use the smaller host size.

>

> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org<mailto:stephen@networkplumber.org>>

> ---

>  lib/librte_pmd_virtio/virtio_ethdev.c | 18 +++++++++++++-----

>  1 file changed, 13 insertions(+), 5 deletions(-)

>

> diff --git a/lib/librte_pmd_virtio/virtio_ethdev.c

> b/lib/librte_pmd_virtio/virtio_ethdev.c

> index 3cb9c6a..db0232e 100644

> --- a/lib/librte_pmd_virtio/virtio_ethdev.c

> +++ b/lib/librte_pmd_virtio/virtio_ethdev.c

> @@ -267,13 +267,21 @@ int virtio_dev_queue_setup(struct rte_eth_dev

> *dev,

>       if (vq_size == 0) {

>               PMD_INIT_LOG(ERR, "%s: virtqueue does not exist",

> __func__);

>               return -EINVAL;

> -     } else if (!rte_is_power_of_2(vq_size)) {

> +     }

> +

> +     if (!rte_is_power_of_2(vq_size)) {

>               PMD_INIT_LOG(ERR, "%s: virtqueue size is not powerof 2",

> __func__);

>               return -EINVAL;

> -     } else if (nb_desc != vq_size) {

> -             PMD_INIT_LOG(ERR, "Warning: nb_desc(%d) is not equal to

> vq size (%d), fall to vq size",

> -                     nb_desc, vq_size);

> -             nb_desc = vq_size;

> +     }

> +

> +     if (nb_desc < vq_size) {

> +             if (!rte_is_power_of_2(nb_desc)) {

> +                     PMD_INIT_LOG(ERR,

> +                                  "nb_desc(%u) size is not powerof 2",

> +                                  nb_desc);

> +                     return -EINVAL;

> +             }

> +             vq_size = nb_desc;

Don't we need a warning when nb_desc > vq_size?

>       }

>

>       if (queue_type == VTNET_RQ) {

> --

> 2.1.4
Thomas Monjalon April 16, 2015, 7:38 a.m. UTC | #4 
Guys, this is an example of what should not be done with emails formatting.

2015-04-16 06:26, Ouyang, Changchun:
> 
> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Thursday, April 16, 2015 1:48 PM
> To: Ouyang, Changchun
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 4/5] virtio: fix ring size negotiation

This header is partly useless.

> 
> No warning is needed, it just works.

Stephen, please do not top post. It makes harder to find what you are commenting.

> 
> I know it works, but the upper user don’t know the descriptor number is reduced.
> I concern it is not so user-friendly here.

Changchun, please be sure the above text is quoted.
How are we supposed to understand who is speaking here?

All, please, take care of readers.
Thanks

> On Wed, Apr 15, 2015 at 8:39 PM, Ouyang, Changchun <changchun.ouyang@intel.com<mailto:changchun.ouyang@intel.com>> wrote:
> 
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org<mailto:dev-bounces@dpdk.org>] On Behalf Of Stephen
> > Hemminger
> > Sent: Wednesday, April 15, 2015 11:20 PM
> > To: dev@dpdk.org<mailto:dev@dpdk.org>
> > Subject: [dpdk-dev] [PATCH 4/5] virtio: fix ring size negotiation
> >
> > This fixes another of the issues with running virtio on non-KVM
> > envirionments. For example, Google Compute Engine reports a ring size of
> > 16K.
> >
> > If guest virtio requests more slots than available then the queue should just
> 
> I suspect 'more' here should be 'less'?
> 
> > be initialized to the smaller value.
> >
> > Conversely, if the number of descriptors requested exceeds the virtio host
> > queue size, then just silently use the smaller host size.
> >
> > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org<mailto:stephen@networkplumber.org>>
> > ---
> >  lib/librte_pmd_virtio/virtio_ethdev.c | 18 +++++++++++++-----
> >  1 file changed, 13 insertions(+), 5 deletions(-)
> >
> > diff --git a/lib/librte_pmd_virtio/virtio_ethdev.c
> > b/lib/librte_pmd_virtio/virtio_ethdev.c
> > index 3cb9c6a..db0232e 100644
> > --- a/lib/librte_pmd_virtio/virtio_ethdev.c
> > +++ b/lib/librte_pmd_virtio/virtio_ethdev.c
> > @@ -267,13 +267,21 @@ int virtio_dev_queue_setup(struct rte_eth_dev
> > *dev,
> >       if (vq_size == 0) {
> >               PMD_INIT_LOG(ERR, "%s: virtqueue does not exist",
> > __func__);
> >               return -EINVAL;
> > -     } else if (!rte_is_power_of_2(vq_size)) {
> > +     }
> > +
> > +     if (!rte_is_power_of_2(vq_size)) {
> >               PMD_INIT_LOG(ERR, "%s: virtqueue size is not powerof 2",
> > __func__);
> >               return -EINVAL;
> > -     } else if (nb_desc != vq_size) {
> > -             PMD_INIT_LOG(ERR, "Warning: nb_desc(%d) is not equal to
> > vq size (%d), fall to vq size",
> > -                     nb_desc, vq_size);
> > -             nb_desc = vq_size;
> > +     }
> > +
> > +     if (nb_desc < vq_size) {
> > +             if (!rte_is_power_of_2(nb_desc)) {
> > +                     PMD_INIT_LOG(ERR,
> > +                                  "nb_desc(%u) size is not powerof 2",
> > +                                  nb_desc);
> > +                     return -EINVAL;
> > +             }
> > +             vq_size = nb_desc;
> Don't we need a warning when nb_desc > vq_size?
> 
> >       }
> >
> >       if (queue_type == VTNET_RQ) {
> > --
> > 2.1.4
> 
>
Stephen Hemminger April 16, 2015, 5:30 p.m. UTC | #5 
On Thu, 16 Apr 2015 09:38:46 +0200
Thomas Monjalon <thomas.monjalon@6wind.com> wrote:

> Guys, this is an example of what should not be done with emails formatting.

Sorry, Google mail client for Android seems to encourage
bad formatting.
Stephen Hemminger April 16, 2015, 5:33 p.m. UTC | #6 
On Thu, 16 Apr 2015 06:26:02 +0000
"Ouyang, Changchun" <changchun.ouyang@intel.com> wrote:

> 
> 
> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Thursday, April 16, 2015 1:48 PM
> To: Ouyang, Changchun
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 4/5] virtio: fix ring size negotiation
> 
> No warning is needed, it just works.
> 
> I know it works, but the upper user don’t know the descriptor number is reduced.
> I concern it is not so user-friendly here.
> 
> 
> On Wed, Apr 15, 2015 at 8:39 PM, Ouyang, Changchun <changchun.ouyang@intel.com<mailto:changchun.ouyang@intel.com>> wrote:
> 
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org<mailto:dev-bounces@dpdk.org>] On Behalf Of Stephen
> > Hemminger
> > Sent: Wednesday, April 15, 2015 11:20 PM
> > To: dev@dpdk.org<mailto:dev@dpdk.org>
> > Subject: [dpdk-dev] [PATCH 4/5] virtio: fix ring size negotiation
> >
> > This fixes another of the issues with running virtio on non-KVM
> > envirionments. For example, Google Compute Engine reports a ring size of
> > 16K.
> >
> > If guest virtio requests more slots than available then the queue should just
> 
> I suspect 'more' here should be 'less'?
> 
> > be initialized to the smaller value.
> >
> > Conversely, if the number of descriptors requested exceeds the virtio host
> > queue size, then just silently use the smaller host size.
> >
> > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org<mailto:stephen@networkplumber.org>>
> > ---
> >  lib/librte_pmd_virtio/virtio_ethdev.c | 18 +++++++++++++-----
> >  1 file changed, 13 insertions(+), 5 deletions(-)
> >
> > diff --git a/lib/librte_pmd_virtio/virtio_ethdev.c
> > b/lib/librte_pmd_virtio/virtio_ethdev.c
> > index 3cb9c6a..db0232e 100644
> > --- a/lib/librte_pmd_virtio/virtio_ethdev.c
> > +++ b/lib/librte_pmd_virtio/virtio_ethdev.c
> > @@ -267,13 +267,21 @@ int virtio_dev_queue_setup(struct rte_eth_dev
> > *dev,
> >       if (vq_size == 0) {
> >               PMD_INIT_LOG(ERR, "%s: virtqueue does not exist",
> > __func__);
> >               return -EINVAL;
> > -     } else if (!rte_is_power_of_2(vq_size)) {
> > +     }
> > +
> > +     if (!rte_is_power_of_2(vq_size)) {
> >               PMD_INIT_LOG(ERR, "%s: virtqueue size is not powerof 2",
> > __func__);
> >               return -EINVAL;
> > -     } else if (nb_desc != vq_size) {
> > -             PMD_INIT_LOG(ERR, "Warning: nb_desc(%d) is not equal to
> > vq size (%d), fall to vq size",
> > -                     nb_desc, vq_size);
> > -             nb_desc = vq_size;
> > +     }
> > +
> > +     if (nb_desc < vq_size) {
> > +             if (!rte_is_power_of_2(nb_desc)) {
> > +                     PMD_INIT_LOG(ERR,
> > +                                  "nb_desc(%u) size is not powerof 2",
> > +                                  nb_desc);
> > +                     return -EINVAL;
> > +             }
> > +             vq_size = nb_desc;
> Don't we need a warning when nb_desc > vq_size?


No warning is needed. This will actually be a common case
for many applications.  

IMHO application should not have to worry about
what type of network device it is running on and therefore would likely
pass a reasonably large number of receive descriptors (say 512) and since
the default KVM/QEMU ring size is 256, the receive queue would be limited
by host not application.

The whole idea of application passing number of receive descriptors to
DPDK is bogus because each device driver has different timing, and may
use different number of receive descriptors per packet.
diff mbox

Patch

diff --git a/lib/librte_pmd_virtio/virtio_ethdev.c b/lib/librte_pmd_virtio/virtio_ethdev.c
index 3cb9c6a..db0232e 100644
--- a/lib/librte_pmd_virtio/virtio_ethdev.c
+++ b/lib/librte_pmd_virtio/virtio_ethdev.c
@@ -267,13 +267,21 @@  int virtio_dev_queue_setup(struct rte_eth_dev *dev,
 	if (vq_size == 0) {
 		PMD_INIT_LOG(ERR, "%s: virtqueue does not exist", __func__);
 		return -EINVAL;
-	} else if (!rte_is_power_of_2(vq_size)) {
+	}
+
+	if (!rte_is_power_of_2(vq_size)) {
 		PMD_INIT_LOG(ERR, "%s: virtqueue size is not powerof 2", __func__);
 		return -EINVAL;
-	} else if (nb_desc != vq_size) {
-		PMD_INIT_LOG(ERR, "Warning: nb_desc(%d) is not equal to vq size (%d), fall to vq size",
-			nb_desc, vq_size);
-		nb_desc = vq_size;
+	}
+
+	if (nb_desc < vq_size) {
+		if (!rte_is_power_of_2(nb_desc)) {
+			PMD_INIT_LOG(ERR,
+				     "nb_desc(%u) size is not powerof 2",
+				     nb_desc);
+			return -EINVAL;
+		}
+		vq_size = nb_desc;
 	}
 
 	if (queue_type == VTNET_RQ) {