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Merge branch 'for-uring-ubufops' into HEAD 

Pavel Begunkov says:

====================
implement io_uring notification (ubuf_info) stacking (net part)

To have per request buffer notifications each zerocopy io_uring send
request allocates a new ubuf_info. However, as an skb can carry only
one uarg, it may force the stack to create many small skbs hurting
performance in many ways.

The patchset implements notification, i.e. an io_uring's ubuf_info
extension, stacking. It attempts to link ubuf_info's into a list,
allowing to have multiple of them per skb.

liburing/examples/send-zerocopy shows up 6 times performance improvement
for TCP with 4KB bytes per send, and levels it with MSG_ZEROCOPY. Without
the patchset it requires much larger sends to utilise all potential.

bytes  | before | after (Kqps)
1200   | 195    | 1023
4000   | 193    | 1386
8000   | 154    | 1058
====================

Link: https://lore.kernel.org/all/cover.1713369317.git.asml.silence@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2024-04-22 16:33:10 -07:00
parent 65f1df1140 65bada80de
commit af046fd169
9 changed files with 69 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/net/tap.c
View File

@ -754,7 +754,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
skb_zcopy_init(skb, msg_control);
} else if (msg_control) {
struct ubuf_info *uarg = msg_control;
uarg->callback(NULL, uarg, false);
uarg->ops->complete(NULL, uarg, false);
}
dev_queue_xmit(skb);

2
drivers/net/tun.c
View File

@ -1906,7 +1906,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
skb_zcopy_init(skb, msg_control);
} else if (msg_control) {
struct ubuf_info *uarg = msg_control;
uarg->callback(NULL, uarg, false);
uarg->ops->complete(NULL, uarg, false);
}
skb_reset_network_header(skb);

5
drivers/net/xen-netback/common.h
View File

@ -390,9 +390,8 @@ bool xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb);
void xenvif_carrier_on(struct xenvif *vif);
/* Callback from stack when TX packet can be released */
void xenvif_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *ubuf,
bool zerocopy_success);
/* Callbacks from stack when TX packet can be released */
extern const struct ubuf_info_ops xenvif_ubuf_ops;
static inline pending_ring_idx_t nr_pending_reqs(struct xenvif_queue *queue)
{

2
drivers/net/xen-netback/interface.c
View File

@ -593,7 +593,7 @@ int xenvif_init_queue(struct xenvif_queue *queue)
for (i = 0; i < MAX_PENDING_REQS; i++) {
queue->pending_tx_info[i].callback_struct = (struct ubuf_info_msgzc)
{ { .callback = xenvif_zerocopy_callback },
{ { .ops = &xenvif_ubuf_ops },
{ { .ctx = NULL,
.desc = i } } };
queue->grant_tx_handle[i] = NETBACK_INVALID_HANDLE;

11
drivers/net/xen-netback/netback.c
View File

@ -1157,7 +1157,7 @@ static int xenvif_handle_frag_list(struct xenvif_queue *queue, struct sk_buff *s
uarg = skb_shinfo(skb)->destructor_arg;
/* increase inflight counter to offset decrement in callback */
atomic_inc(&queue->inflight_packets);
uarg->callback(NULL, uarg, true);
uarg->ops->complete(NULL, uarg, true);
skb_shinfo(skb)->destructor_arg = NULL;
/* Fill the skb with the new (local) frags. */
@ -1279,8 +1279,9 @@ static int xenvif_tx_submit(struct xenvif_queue *queue)
return work_done;
}
void xenvif_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *ubuf_base,
bool zerocopy_success)
static void xenvif_zerocopy_callback(struct sk_buff *skb,
struct ubuf_info *ubuf_base,
bool zerocopy_success)
{
unsigned long flags;
pending_ring_idx_t index;
@ -1313,6 +1314,10 @@ void xenvif_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *ubuf_base,
xenvif_skb_zerocopy_complete(queue);
}
const struct ubuf_info_ops xenvif_ubuf_ops = {
.complete = xenvif_zerocopy_callback,
};
static inline void xenvif_tx_dealloc_action(struct xenvif_queue *queue)
{
struct gnttab_unmap_grant_ref *gop;

8
drivers/vhost/net.c
View File

@ -380,7 +380,7 @@ static void vhost_zerocopy_signal_used(struct vhost_net *net,
}
}
static void vhost_zerocopy_callback(struct sk_buff *skb,
static void vhost_zerocopy_complete(struct sk_buff *skb,
struct ubuf_info *ubuf_base, bool success)
{
struct ubuf_info_msgzc *ubuf = uarg_to_msgzc(ubuf_base);
@ -408,6 +408,10 @@ static void vhost_zerocopy_callback(struct sk_buff *skb,
rcu_read_unlock_bh();
}
static const struct ubuf_info_ops vhost_ubuf_ops = {
.complete = vhost_zerocopy_complete,
};
static inline unsigned long busy_clock(void)
{
return local_clock() >> 10;
@ -879,7 +883,7 @@ static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
ubuf->ctx = nvq->ubufs;
ubuf->desc = nvq->upend_idx;
ubuf->ubuf.callback = vhost_zerocopy_callback;
ubuf->ubuf.ops = &vhost_ubuf_ops;
ubuf->ubuf.flags = SKBFL_ZEROCOPY_FRAG;
refcount_set(&ubuf->ubuf.refcnt, 1);
msg.msg_control = &ctl;

21
include/linux/skbuff.h
View File

@ -527,6 +527,13 @@ enum {
#define SKBFL_ALL_ZEROCOPY (SKBFL_ZEROCOPY_FRAG | SKBFL_PURE_ZEROCOPY | \
SKBFL_DONT_ORPHAN | SKBFL_MANAGED_FRAG_REFS)
struct ubuf_info_ops {
void (*complete)(struct sk_buff *, struct ubuf_info *,
bool zerocopy_success);
/* has to be compatible with skb_zcopy_set() */
int (*link_skb)(struct sk_buff *skb, struct ubuf_info *uarg);
};
/*
* The callback notifies userspace to release buffers when skb DMA is done in
* lower device, the skb last reference should be 0 when calling this.
@ -536,8 +543,7 @@ enum {
* The desc field is used to track userspace buffer index.
*/
struct ubuf_info {
void (*callback)(struct sk_buff *, struct ubuf_info *,
bool zerocopy_success);
const struct ubuf_info_ops *ops;
refcount_t refcnt;
u8 flags;
};
@ -1671,14 +1677,13 @@ static inline void skb_set_end_offset(struct sk_buff *skb, unsigned int offset)
}
#endif
extern const struct ubuf_info_ops msg_zerocopy_ubuf_ops;
struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
struct ubuf_info *uarg);
void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref);
void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
bool success);
int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
struct sk_buff *skb, struct iov_iter *from,
size_t length);
@ -1766,13 +1771,13 @@ static inline void *skb_zcopy_get_nouarg(struct sk_buff *skb)
static inline void net_zcopy_put(struct ubuf_info *uarg)
{
if (uarg)
uarg->callback(NULL, uarg, true);
uarg->ops->complete(NULL, uarg, true);
}
static inline void net_zcopy_put_abort(struct ubuf_info *uarg, bool have_uref)
{
if (uarg) {
if (uarg->callback == msg_zerocopy_callback)
if (uarg->ops == &msg_zerocopy_ubuf_ops)
msg_zerocopy_put_abort(uarg, have_uref);
else if (have_uref)
net_zcopy_put(uarg);
@ -1786,7 +1791,7 @@ static inline void skb_zcopy_clear(struct sk_buff *skb, bool zerocopy_success)
if (uarg) {
if (!skb_zcopy_is_nouarg(skb))
uarg->callback(skb, uarg, zerocopy_success);
uarg->ops->complete(skb, uarg, zerocopy_success);
skb_shinfo(skb)->flags &= ~SKBFL_ALL_ZEROCOPY;
}

18
io_uring/notif.c
View File

@ -24,7 +24,7 @@ static void io_notif_complete_tw_ext(struct io_kiocb *notif, struct io_tw_state
io_req_task_complete(notif, ts);
}
static void io_tx_ubuf_callback(struct sk_buff *skb, struct ubuf_info *uarg,
static void io_tx_ubuf_complete(struct sk_buff *skb, struct ubuf_info *uarg,
bool success)
{
struct io_notif_data *nd = container_of(uarg, struct io_notif_data, uarg);
@ -45,19 +45,27 @@ static void io_tx_ubuf_callback_ext(struct sk_buff *skb, struct ubuf_info *uarg,
else if (!success && !nd->zc_copied)
WRITE_ONCE(nd->zc_copied, true);
}
io_tx_ubuf_callback(skb, uarg, success);
io_tx_ubuf_complete(skb, uarg, success);
}
static const struct ubuf_info_ops io_ubuf_ops = {
.complete = io_tx_ubuf_complete,
};
static const struct ubuf_info_ops io_ubuf_ops_ext = {
.complete = io_tx_ubuf_callback_ext,
};
void io_notif_set_extended(struct io_kiocb *notif)
{
struct io_notif_data *nd = io_notif_to_data(notif);
if (nd->uarg.callback != io_tx_ubuf_callback_ext) {
if (nd->uarg.ops != &io_ubuf_ops_ext) {
nd->account_pages = 0;
nd->zc_report = false;
nd->zc_used = false;
nd->zc_copied = false;
nd->uarg.callback = io_tx_ubuf_callback_ext;
nd->uarg.ops = &io_ubuf_ops_ext;
notif->io_task_work.func = io_notif_complete_tw_ext;
}
}
@ -80,7 +88,7 @@ struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx)
nd = io_notif_to_data(notif);
nd->uarg.flags = IO_NOTIF_UBUF_FLAGS;
nd->uarg.callback = io_tx_ubuf_callback;
nd->uarg.ops = &io_ubuf_ops;
refcount_set(&nd->uarg.refcnt, 1);
return notif;
}

36
net/core/skbuff.c
View File

@ -1652,7 +1652,7 @@ static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
return NULL;
}
uarg->ubuf.callback = msg_zerocopy_callback;
uarg->ubuf.ops = &msg_zerocopy_ubuf_ops;
uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
uarg->len = 1;
uarg->bytelen = size;
@ -1678,7 +1678,7 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
u32 bytelen, next;
/* there might be non MSG_ZEROCOPY users */
if (uarg->callback != msg_zerocopy_callback)
if (uarg->ops != &msg_zerocopy_ubuf_ops)
return NULL;
/* realloc only when socket is locked (TCP, UDP cork),
@ -1789,8 +1789,8 @@ release:
sock_put(sk);
}
void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
bool success)
static void msg_zerocopy_complete(struct sk_buff *skb, struct ubuf_info *uarg,
bool success)
{
struct ubuf_info_msgzc *uarg_zc = uarg_to_msgzc(uarg);
@ -1799,7 +1799,6 @@ void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
if (refcount_dec_and_test(&uarg->refcnt))
__msg_zerocopy_callback(uarg_zc);
}
EXPORT_SYMBOL_GPL(msg_zerocopy_callback);
void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
{
@ -1809,10 +1808,15 @@ void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
uarg_to_msgzc(uarg)->len--;
if (have_uref)
msg_zerocopy_callback(NULL, uarg, true);
msg_zerocopy_complete(NULL, uarg, true);
}
EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
const struct ubuf_info_ops msg_zerocopy_ubuf_ops = {
.complete = msg_zerocopy_complete,
};
EXPORT_SYMBOL_GPL(msg_zerocopy_ubuf_ops);
int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
struct msghdr *msg, int len,
struct ubuf_info *uarg)
@ -1820,11 +1824,18 @@ int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
struct ubuf_info *orig_uarg = skb_zcopy(skb);
int err, orig_len = skb->len;
/* An skb can only point to one uarg. This edge case happens when
* TCP appends to an skb, but zerocopy_realloc triggered a new alloc.
*/
if (orig_uarg && uarg != orig_uarg)
return -EEXIST;
if (uarg->ops->link_skb) {
err = uarg->ops->link_skb(skb, uarg);
if (err)
return err;
} else {
/* An skb can only point to one uarg. This edge case happens
* when TCP appends to an skb, but zerocopy_realloc triggered
* a new alloc.
*/
if (orig_uarg && uarg != orig_uarg)
return -EEXIST;
}
err = __zerocopy_sg_from_iter(msg, sk, skb, &msg->msg_iter, len);
if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) {
@ -1838,7 +1849,8 @@ int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
return err;
}
skb_zcopy_set(skb, uarg, NULL);
if (!uarg->ops->link_skb)
skb_zcopy_set(skb, uarg, NULL);
return skb->len - orig_len;
}
EXPORT_SYMBOL_GPL(skb_zerocopy_iter_stream);