similar to: [PATCH 3 of 5] virtio: support unlocked queue kick

Replace virtqueue_kick by virtqueue_kick_prepare, which requires serialization, and virtqueue_notify, which does not. Repurpose the return values to indicate whether the vq should be notified. This fixes a lock contention with qemu host. When the guest calls vibad rtqueue_notify, the qemu vcpu thread exits the guest and waits for the qemu iothread to perform the MMIO. If the qemu iothread is

Replace virtqueue_kick by virtqueue_kick_prepare, which requires serialization, and virtqueue_notify, which does not. Repurpose the return values to indicate whether the vq should be notified. This fixes a lock contention with qemu host. When the guest calls vibad rtqueue_notify, the qemu vcpu thread exits the guest and waits for the qemu iothread to perform the MMIO. If the qemu iothread is

Replace virtqueue_kick by virtqueue_kick_prepare, which requires serialization, and virtqueue_notify, which does not. Repurpose the return values to indicate whether the vq should be notified. This fixes a bad spinlock contention when the host is qemu. When the guest calls virtqueue_notify, the qemu vcpu thread exits the guest and waits for the qemu iothread to perform the MMIO. If the qemu

On 2018?04?01? 22:12, Tiwei Bie wrote: > Hello everyone, > > This RFC implements packed ring support for virtio driver. > > The code was tested with DPDK vhost (testpmd/vhost-PMD) implemented > by Jens at http://dpdk.org/ml/archives/dev/2018-January/089417.html > Minor changes are needed for the vhost code, e.g. to kick the guest. > > TODO: > - Refinements and bug

On 2018?04?01? 22:12, Tiwei Bie wrote: > Hello everyone, > > This RFC implements packed ring support for virtio driver. > > The code was tested with DPDK vhost (testpmd/vhost-PMD) implemented > by Jens at http://dpdk.org/ml/archives/dev/2018-January/089417.html > Minor changes are needed for the vhost code, e.g. to kick the guest. > > TODO: > - Refinements and bug

A virtio driver does virtqueue_add_buf() multiple times before finally calling virtqueue_kick(); previously we only exposed the added buffers in the virtqueue_kick() call. This means we don't need a memory barrier in virtqueue_add_buf(), but it reduces concurrency as the device (ie. host) can't see the buffers until the kick. Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>

A virtio driver does virtqueue_add_buf() multiple times before finally calling virtqueue_kick(); previously we only exposed the added buffers in the virtqueue_kick() call. This means we don't need a memory barrier in virtqueue_add_buf(), but it reduces concurrency as the device (ie. host) can't see the buffers until the kick. Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>

There are lots of mismatches between comments and codes, this patch do these comment fixes. Signed-off-by: Jiang Biao <benbjiang at tencent.com> --- drivers/virtio/virtio_ring.c | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 5df92c308286..3794c7666a99 100644 ---

Split virtqueue_kick() call into virtqueue_kick_prepare(), which requires serialization, and virtqueue_notify(), which does not. Move the virtqueue_notify() call out of the critical section protected by the queue lock. This avoids triggering a vmexit while holding the lock and thereby fixes a rather bad spinlock contention. Suggested-by: Chia-I Wu <olvaffe at gmail.com> Signed-off-by:

Rather than handing a scatterlist[] and out and in numbers to virtqueue_add_buf(), hand two separate ones which can be chained. I shall refrain from ranting about what a disgusting hack chained scatterlists are. I'll just note that this doesn't make things simpler (see diff). The scatterlists we use can be too large for the stack, so we put them in our device struct and reuse them. But

Rather than handing a scatterlist[] and out and in numbers to virtqueue_add_buf(), hand two separate ones which can be chained. I shall refrain from ranting about what a disgusting hack chained scatterlists are. I'll just note that this doesn't make things simpler (see diff). The scatterlists we use can be too large for the stack, so we put them in our device struct and reuse them. But

Hello everyone, This RFC implements packed ring support for virtio driver. The code was tested with DPDK vhost (testpmd/vhost-PMD) implemented by Jens at http://dpdk.org/ml/archives/dev/2018-January/089417.html Minor changes are needed for the vhost code, e.g. to kick the guest. TODO: - Refinements and bug fixes; - Split into small patches; - Test indirect descriptor support; - Test/fix event

Hello everyone, This RFC implements packed ring support for virtio driver. The code was tested with DPDK vhost (testpmd/vhost-PMD) implemented by Jens at http://dpdk.org/ml/archives/dev/2018-January/089417.html Minor changes are needed for the vhost code, e.g. to kick the guest. TODO: - Refinements and bug fixes; - Split into small patches; - Test indirect descriptor support; - Test/fix event

This commit introduces the support for creating packed ring. All split ring specific functions are added _split suffix. Some necessary stubs for packed ring are also added. Signed-off-by: Tiwei Bie <tiwei.bie at intel.com> --- drivers/virtio/virtio_ring.c | 801 +++++++++++++++++++++++------------ include/linux/virtio_ring.h | 8 +- 2 files changed, 546 insertions(+), 263 deletions(-)

This commit introduces the support for creating packed ring. All split ring specific functions are added _split suffix. Some necessary stubs for packed ring are also added. Signed-off-by: Tiwei Bie <tiwei.bie at intel.com> --- drivers/virtio/virtio_ring.c | 801 +++++++++++++++++++++++------------ include/linux/virtio_ring.h | 8 +- 2 files changed, 546 insertions(+), 263 deletions(-)

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git

Use virtioXX_to_cpu and friends for access to all multibyte structures in memory. Note: this is intentionally mechanical. A follow-up patch will split long lines etc. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/virtio/virtio_ring.c | 89 ++++++++++++++++++++++---------------------- 1 file changed, 45 insertions(+), 44 deletions(-) diff --git