[Qemu-devel] [PATCH] tap: set IFF_ONE_QUEUE per default
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
Signed-off-by: Peter Lieven p...@kamp.de
---
net/tap-linux.c |2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/tap-linux.c b/net/tap-linux.c
index a953189..2759b78 100644
--- a/net/tap-linux.c
+++ b/net/tap-linux.c
@@ -49,7 +49,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
return -1;
}
memset(ifr, 0, sizeof(ifr));
-ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
+ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE;
if (*vnet_hdr) {
unsigned int features;
--
1.7.9.5
Re: [Qemu-devel] [PATCH] tap: set IFF_ONE_QUEUE per default
On Fri, Feb 15, 2013 at 09:27:18AM +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 Signed-off-by: Peter Lieven p...@kamp.de --- net/tap-linux.c |2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Reviewed-by: Stefan Hajnoczi stefa...@redhat.com
Re: [Qemu-devel] [PATCH] tap: set IFF_ONE_QUEUE per default
Am 15.02.2013 um 10:16 schrieb Stefan Hajnoczi stefa...@gmail.com: On Fri, Feb 15, 2013 at 09:27:18AM +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 Signed-off-by: Peter Lieven p...@kamp.de --- net/tap-linux.c |2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Reviewed-by: Stefan Hajnoczi stefa...@redhat.com it seems that IFF_ONE_QUEUE is not defined in qemu headers. i will sent an update. sorry, peter
Re: [Qemu-devel] [PATCH] tap: set IFF_ONE_QUEUE per default
On 15/02/13 09:27, 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
Signed-off-by: Peter Lieven p...@kamp.de
---
net/tap-linux.c |2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/tap-linux.c b/net/tap-linux.c
index a953189..2759b78 100644
--- a/net/tap-linux.c
+++ b/net/tap-linux.c
@@ -49,7 +49,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
return -1;
}
memset(ifr, 0, sizeof(ifr));
-ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
+ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE;
if (*vnet_hdr) {
unsigned int features;
Wouldn't that break macvtap?
there is
case TUNSETIFF:
/* ignore the name, just look at flags */
if (get_user(u, ifr-ifr_flags))
return -EFAULT;
ret = 0;
if ((u ~IFF_VNET_HDR) != (IFF_NO_PI | IFF_TAP))
ret = -EINVAL;
in drivers/net/macvtap.c
Re: [Qemu-devel] [PATCH] tap: set IFF_ONE_QUEUE per default
On 15/02/13 10:25, Peter Lieven wrote:
Am 15.02.2013 um 10:22 schrieb Christian Borntraeger borntrae...@de.ibm.com:
On 15/02/13 09:27, 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
Signed-off-by: Peter Lieven p...@kamp.de
---
net/tap-linux.c |2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/tap-linux.c b/net/tap-linux.c
index a953189..2759b78 100644
--- a/net/tap-linux.c
+++ b/net/tap-linux.c
@@ -49,7 +49,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
return -1;
}
memset(ifr, 0, sizeof(ifr));
-ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
+ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE;
if (*vnet_hdr) {
unsigned int features;
Wouldn't that break macvtap?
there is
case TUNSETIFF:
/* ignore the name, just look at flags */
if (get_user(u, ifr-ifr_flags))
return -EFAULT;
ret = 0;
if ((u ~IFF_VNET_HDR) != (IFF_NO_PI | IFF_TAP))
ret = -EINVAL;
in drivers/net/macvtap.c
wasn`t aware I will modify this to only be set on linux
Peter
macvtap is a Linux driver. It is given to qemu usually via libvirt with
something
like -netdev tap,fd=21,id=hostnet0,vhost=on,vhostfd=22
and then having fd21 pointing to an open /dev/tap... device which is backed by
macvtap.
Christian
Re: [Qemu-devel] [PATCH] tap: set IFF_ONE_QUEUE per default
Am 15.02.2013 um 10:22 schrieb Christian Borntraeger borntrae...@de.ibm.com:
On 15/02/13 09:27, 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
Signed-off-by: Peter Lieven p...@kamp.de
---
net/tap-linux.c |2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/tap-linux.c b/net/tap-linux.c
index a953189..2759b78 100644
--- a/net/tap-linux.c
+++ b/net/tap-linux.c
@@ -49,7 +49,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
return -1;
}
memset(ifr, 0, sizeof(ifr));
-ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
+ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE;
if (*vnet_hdr) {
unsigned int features;
Wouldn't that break macvtap?
there is
case TUNSETIFF:
/* ignore the name, just look at flags */
if (get_user(u, ifr-ifr_flags))
return -EFAULT;
ret = 0;
if ((u ~IFF_VNET_HDR) != (IFF_NO_PI | IFF_TAP))
ret = -EINVAL;
in drivers/net/macvtap.c
wasn`t aware I will modify this to only be set on linux
Peter
