| Message ID | 511E00AF.5070901@dlhnet.de |
|---|---|
| State | New |
| Headers | show |
On Fri, Feb 15, 2013 at 10:32:31AM +0100, Peter Lieven wrote: > historically the kernel queues packets two times. once > at the device and second in qdisc. this is believed to cause > interface stalls if one of these queues overruns. > > setting IFF_ONE_QUEUE is the default in kernels >= 3.8. the > flag is ignored since then. see kernel commit > 5d097109257c03a71845729f8db6b5770c4bbedc > > v2: > - do only set the flag on linux as it breaks macvtap > - define IFF_ONE_QUEUE in tap-linux.h > > Signed-off-by: Peter Lieven <pl@kamp.de> > --- > net/tap-linux.c | 4 ++++ > net/tap-linux.h | 1 + > 2 files changed, 5 insertions(+) > > diff --git a/net/tap-linux.c b/net/tap-linux.c > index a953189..d49f2fd 100644 > --- a/net/tap-linux.c > +++ b/net/tap-linux.c > @@ -51,6 +51,10 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr, > memset(&ifr, 0, sizeof(ifr)); > ifr.ifr_flags = IFF_TAP | IFF_NO_PI; > > +#ifdef __linux__ > + ifr.ifr_flags |= IFF_ONE_QUEUE; > +#endif tap-linux.c <--- notice the filename Perhaps the solution is to try with IFF_ONE_QUEUE. If the result is -EINVAL, try without. Stefan
Am 15.02.2013 um 14:32 schrieb Stefan Hajnoczi <stefanha@gmail.com>: > On Fri, Feb 15, 2013 at 10:32:31AM +0100, Peter Lieven wrote: >> historically the kernel queues packets two times. once >> at the device and second in qdisc. this is believed to cause >> interface stalls if one of these queues overruns. >> >> setting IFF_ONE_QUEUE is the default in kernels >= 3.8. the >> flag is ignored since then. see kernel commit >> 5d097109257c03a71845729f8db6b5770c4bbedc >> >> v2: >> - do only set the flag on linux as it breaks macvtap >> - define IFF_ONE_QUEUE in tap-linux.h >> >> Signed-off-by: Peter Lieven <pl@kamp.de> >> --- >> net/tap-linux.c | 4 ++++ >> net/tap-linux.h | 1 + >> 2 files changed, 5 insertions(+) >> >> diff --git a/net/tap-linux.c b/net/tap-linux.c >> index a953189..d49f2fd 100644 >> --- a/net/tap-linux.c >> +++ b/net/tap-linux.c >> @@ -51,6 +51,10 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr, >> memset(&ifr, 0, sizeof(ifr)); >> ifr.ifr_flags = IFF_TAP | IFF_NO_PI; >> >> +#ifdef __linux__ >> + ifr.ifr_flags |= IFF_ONE_QUEUE; >> +#endif > > tap-linux.c <--- notice the filename i know. is qemu really using it on MACs? Peter > > Perhaps the solution is to try with IFF_ONE_QUEUE. If the result is > -EINVAL, try without. > > Stefan
On 15/02/13 15:27, Peter Lieven wrote: > > Am 15.02.2013 um 14:32 schrieb Stefan Hajnoczi <stefanha@gmail.com>: > >> On Fri, Feb 15, 2013 at 10:32:31AM +0100, Peter Lieven wrote: >>> historically the kernel queues packets two times. once >>> at the device and second in qdisc. this is believed to cause >>> interface stalls if one of these queues overruns. >>> >>> setting IFF_ONE_QUEUE is the default in kernels >= 3.8. the >>> flag is ignored since then. see kernel commit >>> 5d097109257c03a71845729f8db6b5770c4bbedc >>> >>> v2: >>> - do only set the flag on linux as it breaks macvtap >>> - define IFF_ONE_QUEUE in tap-linux.h >>> >>> Signed-off-by: Peter Lieven <pl@kamp.de> >>> --- >>> net/tap-linux.c | 4 ++++ >>> net/tap-linux.h | 1 + >>> 2 files changed, 5 insertions(+) >>> >>> diff --git a/net/tap-linux.c b/net/tap-linux.c >>> index a953189..d49f2fd 100644 >>> --- a/net/tap-linux.c >>> +++ b/net/tap-linux.c >>> @@ -51,6 +51,10 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr, >>> memset(&ifr, 0, sizeof(ifr)); >>> ifr.ifr_flags = IFF_TAP | IFF_NO_PI; >>> >>> +#ifdef __linux__ >>> + ifr.ifr_flags |= IFF_ONE_QUEUE; >>> +#endif >> >> tap-linux.c <--- notice the filename > > i know. is qemu really using it on MACs? > It has nothing todo with Apple products. Its about a linux kernel driver that provides a tap like interface that can be attached to an network interface with MAC-address filtering. http://virt.kernelnewbies.org/MacVTap Christian
On 15.02.2013 14:32, Stefan Hajnoczi wrote: > On Fri, Feb 15, 2013 at 10:32:31AM +0100, Peter Lieven wrote: >> historically the kernel queues packets two times. once >> at the device and second in qdisc. this is believed to cause >> interface stalls if one of these queues overruns. >> >> setting IFF_ONE_QUEUE is the default in kernels >= 3.8. the >> flag is ignored since then. see kernel commit >> 5d097109257c03a71845729f8db6b5770c4bbedc >> >> v2: >> - do only set the flag on linux as it breaks macvtap >> - define IFF_ONE_QUEUE in tap-linux.h >> >> Signed-off-by: Peter Lieven <pl@kamp.de> >> --- >> net/tap-linux.c | 4 ++++ >> net/tap-linux.h | 1 + >> 2 files changed, 5 insertions(+) >> >> diff --git a/net/tap-linux.c b/net/tap-linux.c >> index a953189..d49f2fd 100644 >> --- a/net/tap-linux.c >> +++ b/net/tap-linux.c >> @@ -51,6 +51,10 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr, >> memset(&ifr, 0, sizeof(ifr)); >> ifr.ifr_flags = IFF_TAP | IFF_NO_PI; >> >> +#ifdef __linux__ >> + ifr.ifr_flags |= IFF_ONE_QUEUE; >> +#endif > > tap-linux.c <--- notice the filename > > Perhaps the solution is to try with IFF_ONE_QUEUE. If the result is > -EINVAL, try without. Is IFF_ONE_QUEUE queryable with ioctl(fd, TUNGETFEATURES, &features) ? Peter > > Stefan >
On 18.02.2013 13:39, Peter Lieven wrote: > On 15.02.2013 14:32, Stefan Hajnoczi wrote: >> On Fri, Feb 15, 2013 at 10:32:31AM +0100, Peter Lieven wrote: >>> historically the kernel queues packets two times. once >>> at the device and second in qdisc. this is believed to cause >>> interface stalls if one of these queues overruns. >>> >>> setting IFF_ONE_QUEUE is the default in kernels >= 3.8. the >>> flag is ignored since then. see kernel commit >>> 5d097109257c03a71845729f8db6b5770c4bbedc >>> >>> v2: >>> - do only set the flag on linux as it breaks macvtap >>> - define IFF_ONE_QUEUE in tap-linux.h >>> >>> Signed-off-by: Peter Lieven <pl@kamp.de> >>> --- >>> net/tap-linux.c | 4 ++++ >>> net/tap-linux.h | 1 + >>> 2 files changed, 5 insertions(+) >>> >>> diff --git a/net/tap-linux.c b/net/tap-linux.c >>> index a953189..d49f2fd 100644 >>> --- a/net/tap-linux.c >>> +++ b/net/tap-linux.c >>> @@ -51,6 +51,10 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr, >>> memset(&ifr, 0, sizeof(ifr)); >>> ifr.ifr_flags = IFF_TAP | IFF_NO_PI; >>> >>> +#ifdef __linux__ >>> + ifr.ifr_flags |= IFF_ONE_QUEUE; >>> +#endif >> >> tap-linux.c <--- notice the filename >> >> Perhaps the solution is to try with IFF_ONE_QUEUE. If the result is >> -EINVAL, try without. > > Is IFF_ONE_QUEUE queryable with ioctl(fd, TUNGETFEATURES, &features) ? > > Peter Anyone? Thanks, Peter
On 25/02/13 09:13, Peter Lieven wrote: >> >> Is IFF_ONE_QUEUE queryable with ioctl(fd, TUNGETFEATURES, &features) ? Yes, that should work. The default tun/tap driver returns it, macvtap not.
diff --git a/net/tap-linux.c b/net/tap-linux.c index a953189..d49f2fd 100644 --- a/net/tap-linux.c +++ b/net/tap-linux.c @@ -51,6 +51,10 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr, memset(&ifr, 0, sizeof(ifr)); ifr.ifr_flags = IFF_TAP | IFF_NO_PI; +#ifdef __linux__ + ifr.ifr_flags |= IFF_ONE_QUEUE; +#endif + if (*vnet_hdr) { unsigned int features; diff --git a/net/tap-linux.h b/net/tap-linux.h index 65087e1..13002fd 100644 --- a/net/tap-linux.h +++ b/net/tap-linux.h @@ -36,6 +36,7 @@ /* TUNSETIFF ifr flags */ #define IFF_TAP 0x0002 #define IFF_NO_PI 0x1000 +#define IFF_ONE_QUEUE 0x2000 #define IFF_VNET_HDR 0x4000 #define IFF_MULTI_QUEUE 0x0100 #define IFF_ATTACH_QUEUE 0x0200
historically the kernel queues packets two times. once at the device and second in qdisc. this is believed to cause interface stalls if one of these queues overruns. setting IFF_ONE_QUEUE is the default in kernels >= 3.8. the flag is ignored since then. see kernel commit 5d097109257c03a71845729f8db6b5770c4bbedc v2: - do only set the flag on linux as it breaks macvtap - define IFF_ONE_QUEUE in tap-linux.h Signed-off-by: Peter Lieven <pl@kamp.de> --- net/tap-linux.c | 4 ++++ net/tap-linux.h | 1 + 2 files changed, 5 insertions(+)