In the case of using indirect, indirect desc must be allocated and released each time, which increases a lot of cpu overhead. Here, a cache is added for indirect. If the number of indirect desc to be applied for is less than desc_cache_thr, the desc array with the size of desc_cache_thr is fixed and cached for reuse. Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> --- drivers/virtio/virtio.c | 6 ++ drivers/virtio/virtio_ring.c | 105 ++++++++++++++++++++++++++++++++--- include/linux/virtio.h | 14 +++++ 3 files changed, 117 insertions(+), 8 deletions(-) diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c index 0a5b54034d4b..1047149ac2a4 100644 --- a/drivers/virtio/virtio.c +++ b/drivers/virtio/virtio.c @@ -431,6 +431,12 @@ bool is_virtio_device(struct device *dev) } EXPORT_SYMBOL_GPL(is_virtio_device); +void virtio_set_desc_cache(struct virtio_device *dev, u32 thr) +{ + dev->desc_cache_thr = thr; +} +EXPORT_SYMBOL_GPL(virtio_set_desc_cache); + void unregister_virtio_device(struct virtio_device *dev) { int index = dev->index; /* save for after device release */ diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index dd95dfd85e98..010c47baa37f 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -85,6 +85,19 @@ struct vring_desc_extra { u16 next; /* The next desc state in a list. */ }; +struct vring_desc_cache { + /* desc cache chain */ + struct list_head list; + + void *array; + + /* desc cache threshold + * 0 - disable desc cache + * > 0 - enable desc cache. As the threshold of the desc cache. + */ + u32 thr; +}; + struct vring_virtqueue { struct virtqueue vq; @@ -117,6 +130,8 @@ struct vring_virtqueue { /* Hint for event idx: already triggered no need to disable. */ bool event_triggered; + struct vring_desc_cache desc_cache; + union { /* Available for split ring */ struct { @@ -423,7 +438,76 @@ static unsigned int vring_unmap_one_split(const struct vring_virtqueue *vq, return extra[i].next; } -static struct vring_desc *alloc_indirect_split(struct virtqueue *_vq, +static void desc_cache_free(struct vring_virtqueue *vq) +{ + kfree(vq->desc_cache.array); +} + +static void desc_cache_create(struct vring_virtqueue *vq, + struct virtio_device *vdev, int size, int num) +{ + struct list_head *node; + int i; + + BUILD_BUG_ON(sizeof(struct list_head) > sizeof(struct vring_desc)); + BUILD_BUG_ON(sizeof(struct list_head) > sizeof(struct vring_packed_desc)); + + vq->desc_cache.array = NULL; + vq->desc_cache.thr = vdev->desc_cache_thr; + + INIT_LIST_HEAD(&vq->desc_cache.list); + + if (!vq->desc_cache.thr) + return; + + size = size * vq->desc_cache.thr; + + vq->desc_cache.array = kmalloc_array(num, size, GFP_KERNEL); + if (!vq->desc_cache.array) { + vq->desc_cache.thr = 0; + dev_warn(&vdev->dev, "queue[%d] alloc desc cache fail. turn off it.\n", + vq->vq.index); + return; + } + + for (i = 0; i < num; ++i) { + node = vq->desc_cache.array + (i * size); + list_add(node, &vq->desc_cache.list); + } +} + +static void __desc_cache_put(struct vring_virtqueue *vq, + struct list_head *node, int n) +{ + if (n <= vq->desc_cache.thr) + list_add(node, &vq->desc_cache.list); + else + kfree(node); +} + +#define desc_cache_put(vq, desc, n) \ + __desc_cache_put(vq, (struct list_head *)desc, n) + +static void *desc_cache_get(struct vring_virtqueue *vq, + int size, int n, gfp_t gfp) +{ + struct list_head *node; + + if (n > vq->desc_cache.thr) + return kmalloc_array(n, size, gfp); + + node = vq->desc_cache.list.next; + list_del(node); + return node; +} + +#define _desc_cache_get(vq, n, gfp, tp) \ + ((tp *)desc_cache_get(vq, (sizeof(tp)), n, gfp)) + +#define desc_cache_get_split(vq, n, gfp) \ + _desc_cache_get(vq, n, gfp, struct vring_desc) + +static struct vring_desc *alloc_indirect_split(struct vring_virtqueue *vq, unsigned int total_sg, gfp_t gfp) { @@ -437,12 +521,12 @@ static struct vring_desc *alloc_indirect_split(struct virtqueue *_vq, */ gfp &= ~__GFP_HIGHMEM; - desc = kmalloc_array(total_sg, sizeof(struct vring_desc), gfp); + desc = desc_cache_get_split(vq, total_sg, gfp); if (!desc) return NULL; for (i = 0; i < total_sg; i++) - desc[i].next = cpu_to_virtio16(_vq->vdev, i + 1); + desc[i].next = cpu_to_virtio16(vq->vq.vdev, i + 1); return desc; } @@ -508,7 +592,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, head = vq->free_head; if (virtqueue_use_indirect(_vq, total_sg)) - desc = alloc_indirect_split(_vq, total_sg, gfp); + desc = alloc_indirect_split(vq, total_sg, gfp); else { desc = NULL; WARN_ON_ONCE(total_sg > vq->split.vring.num && !vq->indirect); @@ -652,7 +736,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, } if (indirect) - kfree(desc); + desc_cache_put(vq, desc, total_sg); END_USE(vq); return -ENOMEM; @@ -717,7 +801,7 @@ static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head, if (vq->indirect) { struct vring_desc *indir_desc = vq->split.desc_state[head].indir_desc; - u32 len; + u32 len, n; /* Free the indirect table, if any, now that it's unmapped. */ if (!indir_desc) @@ -729,10 +813,12 @@ static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head, VRING_DESC_F_INDIRECT)); BUG_ON(len == 0 || len % sizeof(struct vring_desc)); - for (j = 0; j < len / sizeof(struct vring_desc); j++) + n = len / sizeof(struct vring_desc); + + for (j = 0; j < n; j++) vring_unmap_one_split_indirect(vq, &indir_desc[j]); - kfree(indir_desc); + desc_cache_put(vq, indir_desc, n); vq->split.desc_state[head].indir_desc = NULL; } else if (ctx) { *ctx = vq->split.desc_state[head].indir_desc; @@ -2200,6 +2286,8 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index, !context; vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX); + desc_cache_create(vq, vdev, sizeof(struct vring_desc), vring.num); + if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM)) vq->weak_barriers = false; @@ -2329,6 +2417,7 @@ void vring_del_virtqueue(struct virtqueue *_vq) if (!vq->packed_ring) { kfree(vq->split.desc_state); kfree(vq->split.desc_extra); + desc_cache_free(vq); } kfree(vq); } diff --git a/include/linux/virtio.h b/include/linux/virtio.h index 41edbc01ffa4..bda6f9853e97 100644 --- a/include/linux/virtio.h +++ b/include/linux/virtio.h @@ -118,6 +118,7 @@ struct virtio_device { struct list_head vqs; u64 features; void *priv; + u32 desc_cache_thr; }; static inline struct virtio_device *dev_to_virtio(struct device *_dev) @@ -130,6 +131,19 @@ int register_virtio_device(struct virtio_device *dev); void unregister_virtio_device(struct virtio_device *dev); bool is_virtio_device(struct device *dev); +/** + * virtio_set_desc_cache - set virtio ring desc cache threshold + * + * virtio will cache the allocated indirect desc. + * + * This function must be called before find_vqs. + * + * @thr: + * 0 - disable desc cache + * > 0 - enable desc cache. As the threshold of the desc cache. + */ +void virtio_set_desc_cache(struct virtio_device *dev, u32 thr); + void virtio_break_device(struct virtio_device *dev); void virtio_config_changed(struct virtio_device *dev); -- 2.31.0 _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization