diff mbox series

[v2,2/3] vhost: move dirty logging cache out of the virtqueue

Message ID 20210316124153.503928-3-maxime.coquelin@redhat.com (mailing list archive)
State Superseded, archived
Delegated to: Maxime Coquelin
Headers
Series vhost: make virtqueue cache-friendly |

Checks

Context Check Description
ci/checkpatch warning coding style issues

Commit Message

Maxime Coquelin March 16, 2021, 12:41 p.m. UTC 
  This patch moves the per-virtqueue's dirty logging cache
out of the virtqueue struct, by allocating it dynamically
only when live-migration is enabled.

It saves 8 cachelines in vhost_virtqueue struct.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/librte_vhost/vhost.c      | 14 ++++++++++++++
 lib/librte_vhost/vhost.h      |  2 +-
 lib/librte_vhost/vhost_user.c | 25 +++++++++++++++++++++++++
 3 files changed, 40 insertions(+), 1 deletion(-)

Comments

David Marchand March 16, 2021, 1:13 p.m. UTC | #1 
On Tue, Mar 16, 2021 at 1:42 PM Maxime Coquelin
<maxime.coquelin@redhat.com> wrote:
>
> This patch moves the per-virtqueue's dirty logging cache
> out of the virtqueue struct, by allocating it dynamically
> only when live-migration is enabled.
>
> It saves 8 cachelines in vhost_virtqueue struct.
>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  lib/librte_vhost/vhost.c      | 14 ++++++++++++++
>  lib/librte_vhost/vhost.h      |  2 +-
>  lib/librte_vhost/vhost_user.c | 25 +++++++++++++++++++++++++
>  3 files changed, 40 insertions(+), 1 deletion(-)
>
> diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
> index 5a7c0c6cff..c3490ce897 100644
> --- a/lib/librte_vhost/vhost.c
> +++ b/lib/librte_vhost/vhost.c
> @@ -145,6 +145,10 @@ __vhost_log_cache_sync(struct virtio_net *dev, struct vhost_virtqueue *vq)
>         if (unlikely(!dev->log_base))
>                 return;
>
> +       /* No cache, nothing to sync */
> +       if (unlikely(!vq->log_cache))
> +               return;
> +
>         rte_atomic_thread_fence(__ATOMIC_RELEASE);
>
>         log_base = (unsigned long *)(uintptr_t)dev->log_base;
> @@ -177,6 +181,14 @@ vhost_log_cache_page(struct virtio_net *dev, struct vhost_virtqueue *vq,
>         uint32_t offset = page / (sizeof(unsigned long) << 3);
>         int i;
>
> +       if (unlikely(!vq->log_cache)) {
> +               /* No logging cache allocated, write dirty log map directly */
> +               rte_smp_wmb();

We try not to reintroduce full barriers (checkpatch caught this).


> +               vhost_log_page((uint8_t *)(uintptr_t)dev->log_base, page);
> +
> +               return;
> +       }
> +
>         for (i = 0; i < vq->log_cache_nb_elem; i++) {
>                 struct log_cache_entry *elem = vq->log_cache + i;
>
> @@ -354,6 +366,8 @@ free_vq(struct virtio_net *dev, struct vhost_virtqueue *vq)
>         }
>         rte_free(vq->batch_copy_elems);
>         rte_mempool_free(vq->iotlb_pool);
> +       if (vq->log_cache)
> +               rte_free(vq->log_cache);

No if() needed.


>         rte_free(vq);
>  }
>
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index 717f410548..3a71dfeed9 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -183,7 +183,7 @@ struct vhost_virtqueue {
>         bool                    used_wrap_counter;
>         bool                    avail_wrap_counter;
>
> -       struct log_cache_entry log_cache[VHOST_LOG_CACHE_NR];
> +       struct log_cache_entry *log_cache;
>         uint16_t log_cache_nb_elem;
>
>         rte_rwlock_t    iotlb_lock;
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index a60bb945ad..0f452d6ff3 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -2022,6 +2022,11 @@ vhost_user_get_vring_base(struct virtio_net **pdev,
>         rte_free(vq->batch_copy_elems);
>         vq->batch_copy_elems = NULL;
>
> +       if (vq->log_cache) {
> +               rte_free(vq->log_cache);
> +               vq->log_cache = NULL;
> +       }

Idem.


> +
>         msg->size = sizeof(msg->payload.state);
>         msg->fd_num = 0;
>
> @@ -2121,6 +2126,7 @@ vhost_user_set_log_base(struct virtio_net **pdev, struct VhostUserMsg *msg,
>         int fd = msg->fds[0];
>         uint64_t size, off;
>         void *addr;
> +       uint32_t i;
>
>         if (validate_msg_fds(msg, 1) != 0)
>                 return RTE_VHOST_MSG_RESULT_ERR;
> @@ -2174,6 +2180,25 @@ vhost_user_set_log_base(struct virtio_net **pdev, struct VhostUserMsg *msg,
>         dev->log_base = dev->log_addr + off;
>         dev->log_size = size;
>
> +       for (i = 0; i < dev->nr_vring; i++) {
> +               struct vhost_virtqueue *vq = dev->virtqueue[i];
> +
> +               if (vq->log_cache) {
> +                       rte_free(vq->log_cache);
> +                       vq->log_cache = NULL;
> +               }

Idem.


> +               vq->log_cache_nb_elem = 0;
> +               vq->log_cache = rte_zmalloc("vq log cache",
> +                               sizeof(struct log_cache_entry) * VHOST_LOG_CACHE_NR,
> +                               0);
> +               /*
> +                * If log cache alloc fail, don't fail migration, but no
> +                * caching will be done, which will impact performance
> +                */
> +               if (!vq->log_cache)
> +                       VHOST_LOG_CONFIG(ERR, "Failed to allocate VQ logging cache\n");
> +       }
> +
>         /*
>          * The spec is not clear about it (yet), but QEMU doesn't expect
>          * any payload in the reply.
> --
> 2.29.2
>
Maxime Coquelin March 17, 2021, 10:20 a.m. UTC | #2 
On 3/16/21 2:13 PM, David Marchand wrote:
> On Tue, Mar 16, 2021 at 1:42 PM Maxime Coquelin
> <maxime.coquelin@redhat.com> wrote:
>>
>> This patch moves the per-virtqueue's dirty logging cache
>> out of the virtqueue struct, by allocating it dynamically
>> only when live-migration is enabled.
>>
>> It saves 8 cachelines in vhost_virtqueue struct.
>>
>> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>> ---
>>  lib/librte_vhost/vhost.c      | 14 ++++++++++++++
>>  lib/librte_vhost/vhost.h      |  2 +-
>>  lib/librte_vhost/vhost_user.c | 25 +++++++++++++++++++++++++
>>  3 files changed, 40 insertions(+), 1 deletion(-)
>>
>> diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
>> index 5a7c0c6cff..c3490ce897 100644
>> --- a/lib/librte_vhost/vhost.c
>> +++ b/lib/librte_vhost/vhost.c
>> @@ -145,6 +145,10 @@ __vhost_log_cache_sync(struct virtio_net *dev, struct vhost_virtqueue *vq)
>>         if (unlikely(!dev->log_base))
>>                 return;
>>
>> +       /* No cache, nothing to sync */
>> +       if (unlikely(!vq->log_cache))
>> +               return;
>> +
>>         rte_atomic_thread_fence(__ATOMIC_RELEASE);
>>
>>         log_base = (unsigned long *)(uintptr_t)dev->log_base;
>> @@ -177,6 +181,14 @@ vhost_log_cache_page(struct virtio_net *dev, struct vhost_virtqueue *vq,
>>         uint32_t offset = page / (sizeof(unsigned long) << 3);
>>         int i;
>>
>> +       if (unlikely(!vq->log_cache)) {
>> +               /* No logging cache allocated, write dirty log map directly */
>> +               rte_smp_wmb();
> 
> We try not to reintroduce full barriers (checkpatch caught this).

Agree, the rebase introduced it again silently.

> 
>> +               vhost_log_page((uint8_t *)(uintptr_t)dev->log_base, page);
>> +
>> +               return;
>> +       }
>> +
>>         for (i = 0; i < vq->log_cache_nb_elem; i++) {
>>                 struct log_cache_entry *elem = vq->log_cache + i;
>>
>> @@ -354,6 +366,8 @@ free_vq(struct virtio_net *dev, struct vhost_virtqueue *vq)
>>         }
>>         rte_free(vq->batch_copy_elems);
>>         rte_mempool_free(vq->iotlb_pool);
>> +       if (vq->log_cache)
>> +               rte_free(vq->log_cache);
> 
> No if() needed.

Yes, will fix in next revision.

> 
>>         rte_free(vq);
>>  }
>>
>> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
>> index 717f410548..3a71dfeed9 100644
>> --- a/lib/librte_vhost/vhost.h
>> +++ b/lib/librte_vhost/vhost.h
>> @@ -183,7 +183,7 @@ struct vhost_virtqueue {
>>         bool                    used_wrap_counter;
>>         bool                    avail_wrap_counter;
>>
>> -       struct log_cache_entry log_cache[VHOST_LOG_CACHE_NR];
>> +       struct log_cache_entry *log_cache;
>>         uint16_t log_cache_nb_elem;
>>
>>         rte_rwlock_t    iotlb_lock;
>> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
>> index a60bb945ad..0f452d6ff3 100644
>> --- a/lib/librte_vhost/vhost_user.c
>> +++ b/lib/librte_vhost/vhost_user.c
>> @@ -2022,6 +2022,11 @@ vhost_user_get_vring_base(struct virtio_net **pdev,
>>         rte_free(vq->batch_copy_elems);
>>         vq->batch_copy_elems = NULL;
>>
>> +       if (vq->log_cache) {
>> +               rte_free(vq->log_cache);
>> +               vq->log_cache = NULL;
>> +       }
> 
> Idem.
> 
> 

Thanks,
Maxime
diff mbox series

Patch

diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
index 5a7c0c6cff..c3490ce897 100644
--- a/lib/librte_vhost/vhost.c
+++ b/lib/librte_vhost/vhost.c
@@ -145,6 +145,10 @@  __vhost_log_cache_sync(struct virtio_net *dev, struct vhost_virtqueue *vq)
 	if (unlikely(!dev->log_base))
 		return;
 
+	/* No cache, nothing to sync */
+	if (unlikely(!vq->log_cache))
+		return;
+
 	rte_atomic_thread_fence(__ATOMIC_RELEASE);
 
 	log_base = (unsigned long *)(uintptr_t)dev->log_base;
@@ -177,6 +181,14 @@  vhost_log_cache_page(struct virtio_net *dev, struct vhost_virtqueue *vq,
 	uint32_t offset = page / (sizeof(unsigned long) << 3);
 	int i;
 
+	if (unlikely(!vq->log_cache)) {
+		/* No logging cache allocated, write dirty log map directly */
+		rte_smp_wmb();
+		vhost_log_page((uint8_t *)(uintptr_t)dev->log_base, page);
+
+		return;
+	}
+
 	for (i = 0; i < vq->log_cache_nb_elem; i++) {
 		struct log_cache_entry *elem = vq->log_cache + i;
 
@@ -354,6 +366,8 @@  free_vq(struct virtio_net *dev, struct vhost_virtqueue *vq)
 	}
 	rte_free(vq->batch_copy_elems);
 	rte_mempool_free(vq->iotlb_pool);
+	if (vq->log_cache)
+		rte_free(vq->log_cache);
 	rte_free(vq);
 }
 
diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
index 717f410548..3a71dfeed9 100644
--- a/lib/librte_vhost/vhost.h
+++ b/lib/librte_vhost/vhost.h
@@ -183,7 +183,7 @@  struct vhost_virtqueue {
 	bool			used_wrap_counter;
 	bool			avail_wrap_counter;
 
-	struct log_cache_entry log_cache[VHOST_LOG_CACHE_NR];
+	struct log_cache_entry *log_cache;
 	uint16_t log_cache_nb_elem;
 
 	rte_rwlock_t	iotlb_lock;
diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index a60bb945ad..0f452d6ff3 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -2022,6 +2022,11 @@  vhost_user_get_vring_base(struct virtio_net **pdev,
 	rte_free(vq->batch_copy_elems);
 	vq->batch_copy_elems = NULL;
 
+	if (vq->log_cache) {
+		rte_free(vq->log_cache);
+		vq->log_cache = NULL;
+	}
+
 	msg->size = sizeof(msg->payload.state);
 	msg->fd_num = 0;
 
@@ -2121,6 +2126,7 @@  vhost_user_set_log_base(struct virtio_net **pdev, struct VhostUserMsg *msg,
 	int fd = msg->fds[0];
 	uint64_t size, off;
 	void *addr;
+	uint32_t i;
 
 	if (validate_msg_fds(msg, 1) != 0)
 		return RTE_VHOST_MSG_RESULT_ERR;
@@ -2174,6 +2180,25 @@  vhost_user_set_log_base(struct virtio_net **pdev, struct VhostUserMsg *msg,
 	dev->log_base = dev->log_addr + off;
 	dev->log_size = size;
 
+	for (i = 0; i < dev->nr_vring; i++) {
+		struct vhost_virtqueue *vq = dev->virtqueue[i];
+
+		if (vq->log_cache) {
+			rte_free(vq->log_cache);
+			vq->log_cache = NULL;
+		}
+		vq->log_cache_nb_elem = 0;
+		vq->log_cache = rte_zmalloc("vq log cache",
+				sizeof(struct log_cache_entry) * VHOST_LOG_CACHE_NR,
+				0);
+		/*
+		 * If log cache alloc fail, don't fail migration, but no
+		 * caching will be done, which will impact performance
+		 */
+		if (!vq->log_cache)
+			VHOST_LOG_CONFIG(ERR, "Failed to allocate VQ logging cache\n");
+	}
+
 	/*
 	 * The spec is not clear about it (yet), but QEMU doesn't expect
 	 * any payload in the reply.