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Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

Browse Source 
Pull virtio updates from Michael Tsirkin:
 "Fixes, cleanups, performance

  A bunch of changes to virtio, most affecting virtio net. Also ptr_ring
  batched zeroing - first of batching enhancements that seems ready."

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  s390/virtio: change maintainership
  tools/virtio: fix spelling mistake: "wakeus" -> "wakeups"
  virtio_net: tidy a couple debug statements
  ptr_ring: support testing different batching sizes
  ringtest: support test specific parameters
  ptr_ring: batch ring zeroing
  virtio: virtio_driver doc
  virtio_net: don't reset twice on XDP on/off
  virtio_net: fix support for small rings
  virtio_net: reduce alignment for buffers
  virtio_net: rework mergeable buffer handling
  virtio_net: allow specifying context for rx
  virtio: allow extra context per descriptor
  tools/virtio: fix build breakage
  virtio: add context flag to find vqs
  virtio: wrap find_vqs
  ringtest: fix an assert statement
This commit is contained in:
Linus Torvalds
2017-05-10 11:33:08 -07:00
parent 5ccd414080 c8b0d72906
commit c44b594303
32 changed files with 330 additions and 146 deletions
Download Patch File Download Diff File Expand all files Collapse all files

63
include/linux/ptr_ring.h
View File

@@ -34,11 +34,13 @@
struct ptr_ring {
int producer ____cacheline_aligned_in_smp;
spinlock_t producer_lock;
int consumer ____cacheline_aligned_in_smp;
int consumer_head ____cacheline_aligned_in_smp; /* next valid entry */
int consumer_tail; /* next entry to invalidate */
spinlock_t consumer_lock;
/* Shared consumer/producer data */
/* Read-only by both the producer and the consumer */
int size ____cacheline_aligned_in_smp; /* max entries in queue */
int batch; /* number of entries to consume in a batch */
void **queue;
};
@@ -170,7 +172,7 @@ static inline int ptr_ring_produce_bh(struct ptr_ring *r, void *ptr)
static inline void *__ptr_ring_peek(struct ptr_ring *r)
{
if (likely(r->size))
return r->queue[r->consumer];
return r->queue[r->consumer_head];
return NULL;
}
@@ -231,9 +233,38 @@ static inline bool ptr_ring_empty_bh(struct ptr_ring *r)
/* Must only be called after __ptr_ring_peek returned !NULL */
static inline void __ptr_ring_discard_one(struct ptr_ring *r)
{
r->queue[r->consumer++] = NULL;
if (unlikely(r->consumer >= r->size))
r->consumer = 0;
/* Fundamentally, what we want to do is update consumer
* index and zero out the entry so producer can reuse it.
* Doing it naively at each consume would be as simple as:
* r->queue[r->consumer++] = NULL;
* if (unlikely(r->consumer >= r->size))
* r->consumer = 0;
* but that is suboptimal when the ring is full as producer is writing
* out new entries in the same cache line. Defer these updates until a
* batch of entries has been consumed.
*/
int head = r->consumer_head++;
/* Once we have processed enough entries invalidate them in
* the ring all at once so producer can reuse their space in the ring.
* We also do this when we reach end of the ring - not mandatory
* but helps keep the implementation simple.
*/
if (unlikely(r->consumer_head - r->consumer_tail >= r->batch ||
r->consumer_head >= r->size)) {
/* Zero out entries in the reverse order: this way we touch the
* cache line that producer might currently be reading the last;
* producer won't make progress and touch other cache lines
* besides the first one until we write out all entries.
*/
while (likely(head >= r->consumer_tail))
r->queue[head--] = NULL;
r->consumer_tail = r->consumer_head;
}
if (unlikely(r->consumer_head >= r->size)) {
r->consumer_head = 0;
r->consumer_tail = 0;
}
}
static inline void *__ptr_ring_consume(struct ptr_ring *r)
@@ -345,14 +376,27 @@ static inline void **__ptr_ring_init_queue_alloc(int size, gfp_t gfp)
return kzalloc(ALIGN(size * sizeof(void *), SMP_CACHE_BYTES), gfp);
}
static inline void __ptr_ring_set_size(struct ptr_ring *r, int size)
{
r->size = size;
r->batch = SMP_CACHE_BYTES * 2 / sizeof(*(r->queue));
/* We need to set batch at least to 1 to make logic
* in __ptr_ring_discard_one work correctly.
* Batching too much (because ring is small) would cause a lot of
* burstiness. Needs tuning, for now disable batching.
*/
if (r->batch > r->size / 2 || !r->batch)
r->batch = 1;
}
static inline int ptr_ring_init(struct ptr_ring *r, int size, gfp_t gfp)
{
r->queue = __ptr_ring_init_queue_alloc(size, gfp);
if (!r->queue)
return -ENOMEM;
r->size = size;
r->producer = r->consumer = 0;
__ptr_ring_set_size(r, size);
r->producer = r->consumer_head = r->consumer_tail = 0;
spin_lock_init(&r->producer_lock);
spin_lock_init(&r->consumer_lock);
@@ -373,9 +417,10 @@ static inline void **__ptr_ring_swap_queue(struct ptr_ring *r, void **queue,
else if (destroy)
destroy(ptr);
r->size = size;
__ptr_ring_set_size(r, size);
r->producer = producer;
r->consumer = 0;
r->consumer_head = 0;
r->consumer_tail = 0;
old = r->queue;
r->queue = queue;

13
include/linux/virtio.h
View File

@@ -44,6 +44,12 @@ int virtqueue_add_inbuf(struct virtqueue *vq,
void *data,
gfp_t gfp);
int virtqueue_add_inbuf_ctx(struct virtqueue *vq,
struct scatterlist sg[], unsigned int num,
void *data,
void *ctx,
gfp_t gfp);
int virtqueue_add_sgs(struct virtqueue *vq,
struct scatterlist *sgs[],
unsigned int out_sgs,
@@ -59,6 +65,9 @@ bool virtqueue_notify(struct virtqueue *vq);
void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len);
void *virtqueue_get_buf_ctx(struct virtqueue *vq, unsigned int *len,
void **ctx);
void virtqueue_disable_cb(struct virtqueue *vq);
bool virtqueue_enable_cb(struct virtqueue *vq);
@@ -156,9 +165,13 @@ int virtio_device_restore(struct virtio_device *dev);
* @feature_table_legacy: same as feature_table but when working in legacy mode.
* @feature_table_size_legacy: number of entries in feature table legacy array.
* @probe: the function to call when a device is found. Returns 0 or -errno.
* @scan: optional function to call after successful probe; intended
* for virtio-scsi to invoke a scan.
* @remove: the function to call when a device is removed.
* @config_changed: optional function to call when the device configuration
* changes; may be called in interrupt context.
* @freeze: optional function to call during suspend/hibernation.
* @restore: optional function to call on resume.
*/
struct virtio_driver {
struct device_driver driver;

25
include/linux/virtio_config.h
View File

@@ -72,7 +72,8 @@ struct virtio_config_ops {
void (*reset)(struct virtio_device *vdev);
int (*find_vqs)(struct virtio_device *, unsigned nvqs,
struct virtqueue *vqs[], vq_callback_t *callbacks[],
const char * const names[], struct irq_affinity *desc);
const char * const names[], const bool *ctx,
struct irq_affinity *desc);
void (*del_vqs)(struct virtio_device *);
u64 (*get_features)(struct virtio_device *vdev);
int (*finalize_features)(struct virtio_device *vdev);
@@ -173,12 +174,32 @@ struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
vq_callback_t *callbacks[] = { c };
const char *names[] = { n };
struct virtqueue *vq;
int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names, NULL);
int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names, NULL,
NULL);
if (err < 0)
return ERR_PTR(err);
return vq;
}
static inline
int virtio_find_vqs(struct virtio_device *vdev, unsigned nvqs,
struct virtqueue *vqs[], vq_callback_t *callbacks[],
const char * const names[],
struct irq_affinity *desc)
{
return vdev->config->find_vqs(vdev, nvqs, vqs, callbacks, names, NULL, desc);
}
static inline
int virtio_find_vqs_ctx(struct virtio_device *vdev, unsigned nvqs,
struct virtqueue *vqs[], vq_callback_t *callbacks[],
const char * const names[], const bool *ctx,
struct irq_affinity *desc)
{
return vdev->config->find_vqs(vdev, nvqs, vqs, callbacks, names, ctx,
desc);
}
/**
* virtio_device_ready - enable vq use in probe function
* @vdev: the device

3
include/linux/virtio_ring.h
View File

@@ -71,6 +71,7 @@ struct virtqueue *vring_create_virtqueue(unsigned int index,
struct virtio_device *vdev,
bool weak_barriers,
bool may_reduce_num,
bool ctx,
bool (*notify)(struct virtqueue *vq),
void (*callback)(struct virtqueue *vq),
const char *name);
@@ -80,6 +81,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
struct vring vring,
struct virtio_device *vdev,
bool weak_barriers,
bool ctx,
bool (*notify)(struct virtqueue *),
void (*callback)(struct virtqueue *),
const char *name);
@@ -93,6 +95,7 @@ struct virtqueue *vring_new_virtqueue(unsigned int index,
unsigned int vring_align,
struct virtio_device *vdev,
bool weak_barriers,
bool ctx,
void *pages,
bool (*notify)(struct virtqueue *vq),
void (*callback)(struct virtqueue *vq),