On Fri, Apr 24, 2015 at 10:47 AM, Stefan Hajnoczi stefa...@gmail.com wrote:
At this level it's compared to vhost-user, but it's not programmable
in userspace!
s/compared/comparable/
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On Fri, 24 Apr 2015 09:04:21 +0200
Cornelia Huck cornelia.h...@de.ibm.com wrote:
On Thu, 23 Apr 2015 21:27:19 +0200
Thomas Huth th...@redhat.com wrote:
Thomas's e-mail did not make it to my mailbox... weird. :-\
On Thu, 23 Apr 2015 17:29:06 +0200
Greg Kurz gk...@linux.vnet.ibm.com wrote:
Hi Stefan,
Great topic. I am also extremely interested in helping Virtio-net become
the standard for the networking industry (the universe of DPDK, etc).
On 22 April 2015 at 19:01, Stefan Hajnoczi stefa...@redhat.com wrote:
[It may be necessary to remove virtio-...@lists.oasis-open.org from CC
On Fri, Apr 24, 2015 at 9:12 AM, Luke Gorrie l...@snabb.co wrote:
- How fast would the new design likely be?
This proposal eliminates two things in the path:
1. Compared to vhost_net, it bypasses the host tun driver and network
stack, replacing it with direct vhost_net - vhost_net data
On Fri, 24 Apr 2015 10:06:19 +0200
Greg Kurz gk...@linux.vnet.ibm.com wrote:
On Fri, 24 Apr 2015 09:19:26 +0200
Cornelia Huck cornelia.h...@de.ibm.com wrote:
On Thu, 23 Apr 2015 17:29:42 +0200
Greg Kurz gk...@linux.vnet.ibm.com wrote:
diff --git a/include/uapi/linux/vhost.h
On Fri, 24 Apr 2015 09:19:26 +0200
Cornelia Huck cornelia.h...@de.ibm.com wrote:
On Thu, 23 Apr 2015 17:29:42 +0200
Greg Kurz gk...@linux.vnet.ibm.com wrote:
This patch brings cross-endian support to vhost when used to implement
legacy virtio devices. Since it is a relatively rare
On 24/04/2015 10:12, Luke Gorrie wrote:
I think this approach could be fruitful in bringing virtio-net to
VM-to-VM networking use cases. Unless virtio-net is extended for this
use case, I'm afraid DPDK and OpenDataPlane communities might steer
clear of VIRTIO.
The current memory accessors logic is:
- little endian if little_endian
- native endian (i.e. no byteswap) if !little_endian
If we want to fully support cross-endian vhost, we also need to be
able to convert to big endian.
Instead of changing the little_endian argument to some 3-value enum, this
On 24 April 2015 at 11:47, Stefan Hajnoczi stefa...@gmail.com wrote:
Incidentally, we also did a pile of work last year on zero-copy NIC-VM
transfers and discovered a lot of interesting problems and edge cases
where
Virtio-net spec and/or drivers are hard to match up with common NICs.
On Fri, Apr 24, 2015 at 1:17 PM, Luke Gorrie l...@snabb.co wrote:
On 24 April 2015 at 11:47, Stefan Hajnoczi stefa...@gmail.com wrote:
My concern is the overhead of the vhost_net component copying
descriptors between NICs.
I see. So you would not have to reserve CPU resources for vswitches.
On Fri, Apr 24, 2015 at 02:24:15PM +0200, Greg Kurz wrote:
Only cosmetic and documentation changes since v5.
---
Looks sane to me. I plan to review and apply next week.
Greg Kurz (8):
virtio: introduce virtio_is_little_endian() helper
tun: add tun_is_little_endian() helper
On Fri, Apr 24, 2015 at 2:10 PM, Luke Gorrie l...@snabb.co wrote:
On 24 April 2015 at 14:17, Luke Gorrie l...@snabb.co wrote:
For what it is worth, I think
Erm, sorry about ranting with my pre-existing ideas without having examined
the proposed specification in detail.
My experience with
Only cosmetic and documentation changes since v5.
---
Greg Kurz (8):
virtio: introduce virtio_is_little_endian() helper
tun: add tun_is_little_endian() helper
macvtap: introduce macvtap_is_little_endian() helper
vringh: introduce vringh_is_little_endian() helper
On 24 April 2015 at 14:17, Luke Gorrie l...@snabb.co wrote:
For what it is worth, I think
Erm, sorry about ranting with my pre-existing ideas without having examined
the proposed specification in detail.
I have a long backlog of things that I have been meaning to discuss with
the Virtio-net
Signed-off-by: Greg Kurz gk...@linux.vnet.ibm.com
---
drivers/vhost/vhost.h | 17 +++--
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 8c1c792..6a49960 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
Signed-off-by: Greg Kurz gk...@linux.vnet.ibm.com
---
include/linux/vringh.h | 17 +++--
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/include/linux/vringh.h b/include/linux/vringh.h
index a3fa537..3ed62ef 100644
--- a/include/linux/vringh.h
+++
Signed-off-by: Greg Kurz gk...@linux.vnet.ibm.com
---
drivers/net/tun.c |9 +++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 857dca4..3c3d6c0 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -206,14 +206,19 @@ struct
Signed-off-by: Greg Kurz gk...@linux.vnet.ibm.com
---
include/linux/virtio_config.h | 17 +++--
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index ca3ed78..bd1a582 100644
---
Signed-off-by: Greg Kurz gk...@linux.vnet.ibm.com
---
drivers/net/macvtap.c |9 +++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 27ecc5c..a2f2958 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -49,14
The VNET_LE flag was introduced to fix accesses to virtio 1.0 headers
that are always little-endian. It can also be used to handle the special
case of a legacy little-endian device implemented by a big-endian host.
Let's add a flag and ioctls for big-endian devices as well. If both flags
are set,
Am Thu, 23 Apr 2015 17:26:20 +0200
schrieb Greg Kurz gk...@linux.vnet.ibm.com:
Signed-off-by: Greg Kurz gk...@linux.vnet.ibm.com
---
include/linux/virtio_config.h | 17 +++--
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/include/linux/virtio_config.h
On Thu, 23 Apr 2015 17:26:52 +0200
Greg Kurz gk...@linux.vnet.ibm.com wrote:
Signed-off-by: Greg Kurz gk...@linux.vnet.ibm.com
---
include/linux/vringh.h | 17 +++--
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/include/linux/vringh.h b/include/linux/vringh.h
On Thu, 23 Apr 2015 17:27:05 +0200
Greg Kurz gk...@linux.vnet.ibm.com wrote:
Signed-off-by: Greg Kurz gk...@linux.vnet.ibm.com
---
drivers/vhost/vhost.h | 17 +++--
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
On Thu, 23 Apr 2015 17:29:06 +0200
Greg Kurz gk...@linux.vnet.ibm.com wrote:
The current memory accessors logic is:
- little endian if little_endian
- native endian (i.e. no byteswap) if !little_endian
If we want to fully support cross-endian vhost, we also need to be
able to convert to
Am Thu, 23 Apr 2015 19:22:15 +0200
schrieb Thomas Huth th...@redhat.com:
Am Thu, 23 Apr 2015 17:26:20 +0200
schrieb Greg Kurz gk...@linux.vnet.ibm.com:
Signed-off-by: Greg Kurz gk...@linux.vnet.ibm.com
---
include/linux/virtio_config.h | 17 +++--
1 file changed, 11
On Thu, 23 Apr 2015 17:26:20 +0200
Greg Kurz gk...@linux.vnet.ibm.com wrote:
Signed-off-by: Greg Kurz gk...@linux.vnet.ibm.com
---
include/linux/virtio_config.h | 17 +++--
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/include/linux/virtio_config.h
On Thu, 23 Apr 2015 17:26:30 +0200
Greg Kurz gk...@linux.vnet.ibm.com wrote:
Signed-off-by: Greg Kurz gk...@linux.vnet.ibm.com
---
drivers/net/tun.c |9 +++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 857dca4..3c3d6c0
On Thu, 23 Apr 2015 17:26:41 +0200
Greg Kurz gk...@linux.vnet.ibm.com wrote:
Signed-off-by: Greg Kurz gk...@linux.vnet.ibm.com
---
drivers/net/macvtap.c |9 +++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index
This patch introduces a new generic queue spinlock implementation that
can serve as an alternative to the default ticket spinlock. Compared
with the ticket spinlock, this queue spinlock should be almost as fair
as the ticket spinlock. It has about the same speed in single-thread
and it can be much
v15-v16:
- Remove the lfsr patch and use linear probing as lfsr is not really
necessary in most cases.
- Move the paravirt PV_CALLEE_SAVE_REGS_THUNK code to an asm header.
- Add a patch to collect PV qspinlock statistics which also
supersedes the PV lock hash debug patch.
- Add PV
This is a preparatory patch that extracts out the following 2 code
snippets to prepare for the next performance optimization patch.
1) the logic for the exchange of new and previous tail code words
into a new xchg_tail() function.
2) the logic for clearing the pending bit and setting the
Currently, atomic_cmpxchg() is used to get the lock. However, this
is not really necessary if there is more than one task in the queue
and the queue head don't need to reset the tail code. For that case,
a simple write to set the lock bit is enough as the queue head will
be the only one eligible
This patch makes the necessary changes at the x86 architecture
specific layer to enable the use of queue spinlock for x86-64. As
x86-32 machines are typically not multi-socket. The benefit of queue
spinlock may not be apparent. So queue spinlock is not enabled.
Currently, there is some
From: Peter Zijlstra (Intel) pet...@infradead.org
Because the qspinlock needs to touch a second cacheline (the per-cpu
mcs_nodes[]); add a pending bit and allow a single in-word spinner
before we punt to the second cacheline.
It is possible so observe the pending bit without the locked bit when
This patch enables the accumulation of PV qspinlock statistics
when either one of the following three sets of CONFIG parameters
are enabled:
1) CONFIG_LOCK_STAT CONFIG_DEBUG_FS
2) CONFIG_KVM_DEBUG_FS
3) CONFIG_XEN_DEBUG_FS
The accumulated lock statistics will be reported in debugfs under the
Before this patch, a CPU may have been kicked twice before getting
the lock - one before it becomes queue head and once before it gets
the lock. All these CPU kicking and halting (VMEXIT) can be expensive
and slow down system performance, especially in an overcommitted guest.
This patch adds a
In the pv_scan_next() function, the slow cmpxchg atomic operation is
performed even if the other CPU is not even close to being halted. This
extra cmpxchg can harm slowpath performance.
This patch introduces the new mayhalt flag to indicate if the other
spinning CPU is close to being halted or
=
CALL FOR PAPERS
10th Workshop on Virtualization in High-Performance Cloud Computing (VHPC
'15)
held in conjunction with Euro-Par 2015, August 24-28, Vienna, Austria
(Springer LNCS)
From: Peter Zijlstra (Intel) pet...@infradead.org
When we allow for a max NR_CPUS 2^14 we can optimize the pending
wait-acquire and the xchg_tail() operations.
By growing the pending bit to a byte, we reduce the tail to 16bit.
This means we can use xchg16 for the tail part and do away with all
This patch adds the necessary KVM specific code to allow KVM to
support the CPU halting and kicking operations needed by the queue
spinlock PV code.
Signed-off-by: Waiman Long waiman.l...@hp.com
---
arch/x86/kernel/kvm.c | 43 +++
kernel/Kconfig.locks |
From: Peter Zijlstra (Intel) pet...@infradead.org
When we detect a hypervisor (!paravirt, see qspinlock paravirt support
patches), revert to a simple test-and-set lock to avoid the horrors
of queue preemption.
Signed-off-by: Peter Zijlstra (Intel) pet...@infradead.org
Signed-off-by: Waiman Long
From: Peter Zijlstra (Intel) pet...@infradead.org
We use the regular paravirt call patching to switch between:
native_queue_spin_lock_slowpath() __pv_queue_spin_lock_slowpath()
native_queue_spin_unlock()__pv_queue_spin_unlock()
We use a callee saved call for the unlock
Provide a separate (second) version of the spin_lock_slowpath for
paravirt along with a special unlock path.
The second slowpath is generated by adding a few pv hooks to the
normal slowpath, but where those will compile away for the native
case, they expand into special wait/wake code for the pv
From: David Vrabel david.vra...@citrix.com
This patch adds the necessary Xen specific code to allow Xen to
support the CPU halting and kicking operations needed by the queue
spinlock PV code.
Signed-off-by: David Vrabel david.vra...@citrix.com
Signed-off-by: Waiman Long waiman.l...@hp.com
---
On Thu, 23 Apr 2015 21:27:19 +0200
Thomas Huth th...@redhat.com wrote:
On Thu, 23 Apr 2015 17:29:06 +0200
Greg Kurz gk...@linux.vnet.ibm.com wrote:
The current memory accessors logic is:
- little endian if little_endian
- native endian (i.e. no byteswap) if !little_endian
If we
On Thu, 23 Apr 2015 17:29:42 +0200
Greg Kurz gk...@linux.vnet.ibm.com wrote:
This patch brings cross-endian support to vhost when used to implement
legacy virtio devices. Since it is a relatively rare situation, the
feature availability is controlled by a kernel config option (not set
by
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