On Wed, Jan 23, 2013 at 09:59:12PM +0800, Jason Wang wrote: > A MAX_TAP_QUEUES(1024) queues of tuntap device is always allocated > unconditionally even userspace only requires a single queue device. This is > unnecessary and will lead a very high order of page allocation when has a high > possibility to fail. Solving this by creating a one queue net device when > userspace only use one queue and also reduce MAX_TAP_QUEUES to > DEFAULT_MAX_NUM_RSS_QUEUES which can guarantee the success of > the allocation. > > Reported-by: Dirk Hohndel <[email protected]> > Cc: Eric Dumazet <[email protected]> > Cc: David Woodhouse <[email protected]> > Cc: Michael S. Tsirkin <[email protected]> > Signed-off-by: Jason Wang <[email protected]>
Note: this is a 3.8 patch, it fixes a regression. Acked-by: Michael S. Tsirkin <[email protected]> > --- > drivers/net/tun.c | 15 ++++++++------- > 1 files changed, 8 insertions(+), 7 deletions(-) > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > index c81680d..8939d21 100644 > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -109,11 +109,10 @@ struct tap_filter { > unsigned char addr[FLT_EXACT_COUNT][ETH_ALEN]; > }; > > -/* 1024 is probably a high enough limit: modern hypervisors seem to support > on > - * the order of 100-200 CPUs so this leaves us some breathing space if we > want > - * to match a queue per guest CPU. > - */ > -#define MAX_TAP_QUEUES 1024 > +/* DEFAULT_MAX_NUM_RSS_QUEUES were choosed 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 > > #define TUN_FLOW_EXPIRE (3 * HZ) > > @@ -1583,6 +1582,8 @@ static int tun_set_iff(struct net *net, struct file > *file, struct ifreq *ifr) > else { > char *name; > unsigned long flags = 0; > + int queues = ifr->ifr_flags & IFF_MULTI_QUEUE ? > + MAX_TAP_QUEUES : 1; > > if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) > return -EPERM; > @@ -1606,8 +1607,8 @@ static int tun_set_iff(struct net *net, struct file > *file, struct ifreq *ifr) > name = ifr->ifr_name; > > dev = alloc_netdev_mqs(sizeof(struct tun_struct), name, > - tun_setup, > - MAX_TAP_QUEUES, MAX_TAP_QUEUES); > + tun_setup, queues, queues); > + > if (!dev) > return -ENOMEM; > > -- > 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
