Messages in this thread | | | Date | Wed, 3 Dec 2014 11:52:10 +0200 | From | "Michael S. Tsirkin" <> | Subject | Re: [PATCH v3 net-next 2/2 tuntap: Increase the number of queues in tun. |
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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)?
> --- > 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
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