[PATCH net-next] Increase limit of macvtap queues

[PATCH net-next] Increase limit of macvtap queues

[Pankaj Gupta]

Macvtap should be compatible with tuntap for maximum number
of queues. '1059590254fa9dce9cafc4f07d1103dbec415e76' removes
the limitation and increases number of queues in tuntap.
Now, Its safe to increase number of queues in Macvtap as well.

Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
---
 include/linux/if_macvlan.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/linux/if_macvlan.h b/include/linux/if_macvlan.h
index 6f6929e..a4ccc31 100644
--- a/include/linux/if_macvlan.h
+++ b/include/linux/if_macvlan.h
@@ -29,7 +29,7 @@ struct macvtap_queue;
  * Maximum times a macvtap device can be opened. This can be used to
  * configure the number of receive queue, e.g. for multiqueue virtio.
  */
-#define MAX_MACVTAP_QUEUES     16
+#define MAX_MACVTAP_QUEUES     256

 #define MACVLAN_MC_FILTER_BITS 8
 #define MACVLAN_MC_FILTER_SZ   (1 << MACVLAN_MC_FILTER_BITS)
--
1.7.1

Re: [PATCH net-next] Increase limit of macvtap queues

[Sergei Shtylyov]

Hello.

On 06/12/2015 04:30 PM, Pankaj Gupta wrote:

> Macvtap should be compatible with tuntap for maximum number
> of queues. '1059590254fa9dce9cafc4f07d1103dbec415e76' removes

    Please also specify that commit's summary line in parens.

> the limitation and increases number of queues in tuntap.
> Now, Its safe to increase number of queues in Macvtap as well.

> Signed-off-by: Pankaj Gupta <pagupta@redhat.com>

WBR, Sergei

Re: [PATCH net-next] Increase limit of macvtap queues

[Michael S. Tsirkin]

On Fri, Jun 12, 2015 at 07:00:28PM +0530, Pankaj Gupta wrote:
> Macvtap should be compatible with tuntap for maximum number
> of queues. '1059590254fa9dce9cafc4f07d1103dbec415e76' removes
> the limitation and increases number of queues in tuntap.
> Now, Its safe to increase number of queues in Macvtap as well.
> 
> Signed-off-by: Pankaj Gupta <pagupta@redhat.com>

It's a good idea, but this might be a problem:

static void macvtap_del_queues(struct net_device *dev)
{
        struct macvlan_dev *vlan = netdev_priv(dev);
        struct macvtap_queue *q, *tmp, *qlist[MAX_MACVTAP_QUEUES];

...
}

by itself, this will use 2K on stack, which seems too much.

You need to rework this function to use a linked list + list_move
instead of an array + list_del_init.

> ---
>  include/linux/if_macvlan.h |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/include/linux/if_macvlan.h b/include/linux/if_macvlan.h
> index 6f6929e..a4ccc31 100644
> --- a/include/linux/if_macvlan.h
> +++ b/include/linux/if_macvlan.h
> @@ -29,7 +29,7 @@ struct macvtap_queue;
>   * Maximum times a macvtap device can be opened. This can be used to
>   * configure the number of receive queue, e.g. for multiqueue virtio.
>   */
> -#define MAX_MACVTAP_QUEUES     16
> +#define MAX_MACVTAP_QUEUES     256
> 
>  #define MACVLAN_MC_FILTER_BITS 8
>  #define MACVLAN_MC_FILTER_SZ   (1 << MACVLAN_MC_FILTER_BITS)
> --
> 1.7.1

Re: [PATCH net-next] Increase limit of macvtap queues

[Jason Wang]

On 06/14/2015 04:42 PM, Michael S. Tsirkin wrote:
> On Fri, Jun 12, 2015 at 07:00:28PM +0530, Pankaj Gupta wrote:
>> Macvtap should be compatible with tuntap for maximum number
>> of queues. '1059590254fa9dce9cafc4f07d1103dbec415e76' removes
>> the limitation and increases number of queues in tuntap.
>> Now, Its safe to increase number of queues in Macvtap as well.
>>
>> Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
> It's a good idea, but this might be a problem:
>
> static void macvtap_del_queues(struct net_device *dev)
> {
>         struct macvlan_dev *vlan = netdev_priv(dev);
>         struct macvtap_queue *q, *tmp, *qlist[MAX_MACVTAP_QUEUES];
>
> ...
> }
>
> by itself, this will use 2K on stack, which seems too much.
>
> You need to rework this function to use a linked list + list_move
> instead of an array + list_del_init.

Looks like even simpler, we can just do sock_put() inside
list_for_each_entry_safe() loop.

>> ---
>>  include/linux/if_macvlan.h |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/include/linux/if_macvlan.h b/include/linux/if_macvlan.h
>> index 6f6929e..a4ccc31 100644
>> --- a/include/linux/if_macvlan.h
>> +++ b/include/linux/if_macvlan.h
>> @@ -29,7 +29,7 @@ struct macvtap_queue;
>>   * Maximum times a macvtap device can be opened. This can be used to
>>   * configure the number of receive queue, e.g. for multiqueue virtio.
>>   */
>> -#define MAX_MACVTAP_QUEUES     16
>> +#define MAX_MACVTAP_QUEUES     256
>>
>>  #define MACVLAN_MC_FILTER_BITS 8
>>  #define MACVLAN_MC_FILTER_SZ   (1 << MACVLAN_MC_FILTER_BITS)
>> --
>> 1.7.1
> --
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