similar to: [PATCH] vhost: cache used event for better performance

On Wed, Jul 26, 2017 at 04:03:17PM +0800, Jason Wang wrote: > This reverts commit 809ecb9bca6a9424ccd392d67e368160f8b76c92. Since it > was reported to break vhost_net. We want to cache used event and use > it to check for notification. We try to valid cached used event by > checking whether or not it was ahead of new, but this is not correct > all the time, it could be stale and

This reverts commit 809ecb9bca6a9424ccd392d67e368160f8b76c92. Since it was reported to break vhost_net. We want to cache used event and use it to check for notification. The assumption was that guest won't move the event idx back, but this could happen in fact when 16 bit index wraps around after 64K entries. Signed-off-by: Jason Wang <jasowang at redhat.com> --- - Changes from V1:

This reverts commit 809ecb9bca6a9424ccd392d67e368160f8b76c92. Since it was reported to break vhost_net. We want to cache used event and use it to check for notification. The assumption was that guest won't move the event idx back, but this could happen in fact when 16 bit index wraps around after 64K entries. Signed-off-by: Jason Wang <jasowang at redhat.com> --- - Changes from V1:

This reverts commit 809ecb9bca6a9424ccd392d67e368160f8b76c92. Since it was reported to break vhost_net. We want to cache used event and use it to check for notification. We try to valid cached used event by checking whether or not it was ahead of new, but this is not correct all the time, it could be stale and there's no way to know about this. Signed-off-by: Jason Wang <jasowang at

This reverts commit 809ecb9bca6a9424ccd392d67e368160f8b76c92. Since it was reported to break vhost_net. We want to cache used event and use it to check for notification. We try to valid cached used event by checking whether or not it was ahead of new, but this is not correct all the time, it could be stale and there's no way to know about this. Signed-off-by: Jason Wang <jasowang at

On Wed, 2017-07-26 at 19:08 +0300, Michael S. Tsirkin wrote: > On Wed, Jul 26, 2017 at 09:37:15PM +0800, Jason Wang wrote: > > > > > > On 2017?07?26? 21:18, Jason Wang wrote: > > > > > > > > > On 2017?07?26? 20:57, Michael S. Tsirkin wrote: > > > > On Wed, Jul 26, 2017 at 04:03:17PM +0800, Jason Wang wrote: > > > > >

On 2017?07?30? 14:26, K. Den wrote: > On Wed, 2017-07-26 at 19:08 +0300, Michael S. Tsirkin wrote: >> On Wed, Jul 26, 2017 at 09:37:15PM +0800, Jason Wang wrote: >>> >>> On 2017?07?26? 21:18, Jason Wang wrote: >>>> >>>> On 2017?07?26? 20:57, Michael S. Tsirkin wrote: >>>>> On Wed, Jul 26, 2017 at 04:03:17PM +0800, Jason Wang wrote:

On 2017?07?30? 14:26, K. Den wrote: > On Wed, 2017-07-26 at 19:08 +0300, Michael S. Tsirkin wrote: >> On Wed, Jul 26, 2017 at 09:37:15PM +0800, Jason Wang wrote: >>> >>> On 2017?07?26? 21:18, Jason Wang wrote: >>>> >>>> On 2017?07?26? 20:57, Michael S. Tsirkin wrote: >>>>> On Wed, Jul 26, 2017 at 04:03:17PM +0800, Jason Wang wrote:

When device IOTLB is enabled, all address translations were stored in interval tree. O(lgN) searching time could be slow for virtqueue metadata (avail, used and descriptors) since they were accessed much often than other addresses. So this patch introduces an O(1) array which points to the interval tree nodes that store the translations of vq metadata. Those array were update during vq IOTLB

When device IOTLB is enabled, all address translations were stored in interval tree. O(lgN) searching time could be slow for virtqueue metadata (avail, used and descriptors) since they were accessed much often than other addresses. So this patch introduces an O(1) array which points to the interval tree nodes that store the translations of vq metadata. Those array were update during vq IOTLB

When device IOTLB is enabled, all address translations were stored in interval tree. O(lgN) searching time could be slow for virtqueue metadata (avail, used and descriptors) since they were accessed much often than other addresses. So this patch introduces an O(1) array which points to the interval tree nodes that store the translations of vq metadata. Those array were update during vq IOTLB

When device IOTLB is enabled, all address translations were stored in interval tree. O(lgN) searching time could be slow for virtqueue metadata (avail, used and descriptors) since they were accessed much often than other addresses. So this patch introduces an O(1) array which points to the interval tree nodes that store the translations of vq metadata. Those array were update during vq IOTLB

On Wed, Jul 26, 2017 at 09:37:15PM +0800, Jason Wang wrote: > > > On 2017?07?26? 21:18, Jason Wang wrote: > > > > > > On 2017?07?26? 20:57, Michael S. Tsirkin wrote: > > > On Wed, Jul 26, 2017 at 04:03:17PM +0800, Jason Wang wrote: > > > > This reverts commit 809ecb9bca6a9424ccd392d67e368160f8b76c92. Since it > > > > was reported to

On Wed, Jul 26, 2017 at 09:37:15PM +0800, Jason Wang wrote: > > > On 2017?07?26? 21:18, Jason Wang wrote: > > > > > > On 2017?07?26? 20:57, Michael S. Tsirkin wrote: > > > On Wed, Jul 26, 2017 at 04:03:17PM +0800, Jason Wang wrote: > > > > This reverts commit 809ecb9bca6a9424ccd392d67e368160f8b76c92. Since it > > > > was reported to

Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/vhost/vhost.c | 93 +++++++++++++++++++++++++++++++-------------------- 1 file changed, 56 insertions(+), 37 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index c90f437..4d379ed 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -33,8 +33,8 @@ enum { VHOST_MEMORY_F_LOG = 0x1, };

Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/vhost/vhost.c | 93 +++++++++++++++++++++++++++++++-------------------- 1 file changed, 56 insertions(+), 37 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index c90f437..4d379ed 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -33,8 +33,8 @@ enum { VHOST_MEMORY_F_LOG = 0x1, };

Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/vhost/vhost.c | 86 +++++++++++++++++++++++++++++---------------------- 1 file changed, 49 insertions(+), 37 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 6a40837..ed71b53 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -33,8 +33,8 @@ enum { VHOST_MEMORY_F_LOG = 0x1, };

Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/vhost/vhost.c | 86 +++++++++++++++++++++++++++++---------------------- 1 file changed, 49 insertions(+), 37 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 6a40837..ed71b53 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -33,8 +33,8 @@ enum { VHOST_MEMORY_F_LOG = 0x1, };

Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/vhost/vhost.c | 93 +++++++++++++++++++++++++++++++-------------------- 1 file changed, 56 insertions(+), 37 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index c90f437..4d379ed 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -33,8 +33,8 @@ enum { VHOST_MEMORY_F_LOG = 0x1, };

Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- drivers/vhost/vhost.c | 93 +++++++++++++++++++++++++++++++-------------------- 1 file changed, 56 insertions(+), 37 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index c90f437..4d379ed 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -33,8 +33,8 @@ enum { VHOST_MEMORY_F_LOG = 0x1, };