From: Jason Wang <jasowang@redhat•com>
To: "Michael S. Tsirkin" <mst@redhat•com>
Cc: Pankaj Gupta <pagupta@redhat•com>,
linux-kernel@vger•kernel.org, netdev@vger•kernel.org,
davem@davemloft•net, dgibson@redhat•com, vfalico@gmail•com,
edumazet@google•com, vyasevic@redhat•com, hkchu@google•com,
wuzhy@linux•vnet.ibm.com, xemul@parallels•com,
therbert@google•com, bhutchings@solarflare•com, xii@google•com,
stephen@networkplumber•org, jiri@resnulli•us,
sergei.shtylyov@cogentembedded•com
Subject: Re: [PATCH v3 net-next 2/2 tuntap: Increase the number of queues in tun.
Date: Thu, 04 Dec 2014 03:03:34 +0008 [thread overview]
Message-ID: <1417661734.16500.0@smtp.corp.redhat.com> (raw)
In-Reply-To: <20141203095210.GC9487@redhat.com>
On Wed, Dec 3, 2014 at 5:52 PM, Michael S. Tsirkin <mst@redhat•com>
wrote:
> On Wed, Dec 03, 2014 at 12:49:37PM +0530, Pankaj Gupta wrote:
>> Networking under kvm works best if we allocate a per-vCPU RX and TX
>> queue in a virtual NIC. This requires a per-vCPU queue on the host
>> side.
>>
>> It is now safe to increase the maximum number of queues.
>> Preceding patche: 'net: allow large number of rx queues'
>
> s/patche/patch/
>
>> made sure this won't cause failures due to high order memory
>> allocations. Increase it to 256: this is the max number of vCPUs
>> KVM supports.
>>
>> Signed-off-by: Pankaj Gupta <pagupta@redhat•com>
>> Reviewed-by: David Gibson <dgibson@redhat•com>
>
> Hmm it's kind of nasty that each tun device is now using x16 memory.
> Maybe we should look at using a flex array instead, and removing the
> limitation altogether (e.g. make it INT_MAX)?
But this only happens when IFF_MULTIQUEUE were used.
And core has vmalloc() fallback.
So probably not a big issue?
>
>
>
>> ---
>> drivers/net/tun.c | 9 +++++----
>> 1 file changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
>> index e3fa65a..a19dc5f8 100644
>> --- a/drivers/net/tun.c
>> +++ b/drivers/net/tun.c
>> @@ -113,10 +113,11 @@ struct tap_filter {
>> unsigned char addr[FLT_EXACT_COUNT][ETH_ALEN];
>> };
>>
>> -/* DEFAULT_MAX_NUM_RSS_QUEUES were chosen to let the rx/tx queues
>> allocated for
>> - * the netdevice to be fit in one page. So we can make sure the
>> success of
>> - * memory allocation. TODO: increase the limit. */
>> -#define MAX_TAP_QUEUES DEFAULT_MAX_NUM_RSS_QUEUES
>> +/* MAX_TAP_QUEUES 256 is chosen to allow rx/tx queues to be equal
>> + * to max number of vCPUS in guest. Also, we are making sure here
>> + * queue memory allocation do not fail.
>
> It's not queue memory allocation anymore, is it?
> I would say "
> This also helps the tfiles field fit in 4K, so the whole tun
> device only needs an order-1 allocation.
> "
>
>> + */
>> +#define MAX_TAP_QUEUES 256
>> #define MAX_TAP_FLOWS 4096
>>
>> #define TUN_FLOW_EXPIRE (3 * HZ)
>> --
>> 1.8.3.1
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe netdev" in
>> the body of a message to majordomo@vger•kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2014-12-04 2:55 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-03 7:19 [PATCH v3 net-net 0/2] Increase the limit of tuntap queues Pankaj Gupta
2014-12-03 7:19 ` [PATCH v3 net-next 1/2] net: allow large number of rx queues Pankaj Gupta
2014-12-03 9:42 ` Michael S. Tsirkin
2014-12-04 10:45 ` Pankaj Gupta
2014-12-03 7:19 ` [PATCH v3 net-next 2/2 tuntap: Increase the number of queues in tun Pankaj Gupta
2014-12-03 9:52 ` Michael S. Tsirkin
2014-12-04 2:55 ` Jason Wang [this message]
2014-12-04 10:20 ` Michael S. Tsirkin
2014-12-04 10:42 ` Pankaj Gupta
2014-12-05 7:35 ` Jason Wang
2014-12-10 7:56 ` Pankaj Gupta
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