io_uring: notification completion optimisation
We want to use all optimisations that we have for io_uring requests like
completion batching, memory caching and more but for zc notifications.
Fortunately, notification perfectly fit the request model so we can
overlay them onto struct io_kiocb and use all the infratructure.
Most of the fields of struct io_notif natively fits into io_kiocb, so we
replace struct io_notif with struct io_kiocb carrying struct
io_notif_data in the cmd cache line. Then we adapt io_alloc_notif() to
use io_alloc_req()/io_alloc_req_refill(), and kill leftovers of hand
coded caching. __io_notif_complete_tw() is converted to use io_uring's
tw infra.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9e010125175e80baf51f0ca63bdc7cc6a4a9fa56.1658913593.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 144493c..f7fab37 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -249,9 +249,6 @@ struct io_ring_ctx {
struct xarray io_bl_xa;
struct list_head io_buffers_cache;
- /* struct io_notif cache, protected by uring_lock */
- struct list_head notif_list;
-
struct io_hash_table cancel_table_locked;
struct list_head cq_overflow_list;
struct io_alloc_cache apoll_cache;
@@ -262,10 +259,6 @@ struct io_ring_ctx {
struct io_wq_work_list locked_free_list;
unsigned int locked_free_nr;
- /* struct io_notif cache protected by completion_lock */
- struct list_head notif_list_locked;
- unsigned int notif_locked_nr;
-
const struct cred *sq_creds; /* cred used for __io_sq_thread() */
struct io_sq_data *sq_data; /* if using sq thread polling */
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 822819d..b54218d 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -321,8 +321,6 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
INIT_WQ_LIST(&ctx->locked_free_list);
INIT_DELAYED_WORK(&ctx->fallback_work, io_fallback_req_func);
INIT_WQ_LIST(&ctx->submit_state.compl_reqs);
- INIT_LIST_HEAD(&ctx->notif_list);
- INIT_LIST_HEAD(&ctx->notif_list_locked);
return ctx;
err:
kfree(ctx->dummy_ubuf);
@@ -2466,7 +2464,6 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
WARN_ON_ONCE(!list_empty(&ctx->ltimeout_list));
WARN_ON_ONCE(ctx->notif_slots || ctx->nr_notif_slots);
- io_notif_cache_purge(ctx);
io_mem_free(ctx->rings);
io_mem_free(ctx->sq_sqes);
diff --git a/io_uring/net.c b/io_uring/net.c
index 8276b95..32fc3da 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -946,7 +946,7 @@ int io_sendzc(struct io_kiocb *req, unsigned int issue_flags)
struct io_ring_ctx *ctx = req->ctx;
struct io_sendzc *zc = io_kiocb_to_cmd(req);
struct io_notif_slot *notif_slot;
- struct io_notif *notif;
+ struct io_kiocb *notif;
struct msghdr msg;
struct iovec iov;
struct socket *sock;
@@ -1005,7 +1005,7 @@ int io_sendzc(struct io_kiocb *req, unsigned int issue_flags)
min_ret = iov_iter_count(&msg.msg_iter);
msg.msg_flags = msg_flags;
- msg.msg_ubuf = ¬if->uarg;
+ msg.msg_ubuf = &io_notif_to_data(notif)->uarg;
msg.sg_from_iter = io_sg_from_iter;
ret = sock_sendmsg(sock, &msg);
diff --git a/io_uring/notif.c b/io_uring/notif.c
index e986a0e..b5f989d 100644
--- a/io_uring/notif.c
+++ b/io_uring/notif.c
@@ -9,140 +9,79 @@
#include "notif.h"
#include "rsrc.h"
-static void __io_notif_complete_tw(struct callback_head *cb)
+static void __io_notif_complete_tw(struct io_kiocb *notif, bool *locked)
{
- struct io_notif *notif = container_of(cb, struct io_notif, task_work);
- struct io_rsrc_node *rsrc_node = notif->rsrc_node;
+ struct io_notif_data *nd = io_notif_to_data(notif);
struct io_ring_ctx *ctx = notif->ctx;
- if (notif->account_pages && ctx->user) {
- __io_unaccount_mem(ctx->user, notif->account_pages);
- notif->account_pages = 0;
+ if (nd->account_pages && ctx->user) {
+ __io_unaccount_mem(ctx->user, nd->account_pages);
+ nd->account_pages = 0;
}
- if (likely(notif->task)) {
- io_put_task(notif->task, 1);
- notif->task = NULL;
- }
-
- io_cq_lock(ctx);
- io_fill_cqe_aux(ctx, notif->tag, 0, notif->seq, true);
-
- list_add(¬if->cache_node, &ctx->notif_list_locked);
- ctx->notif_locked_nr++;
- io_cq_unlock_post(ctx);
-
- io_rsrc_put_node(rsrc_node, 1);
- percpu_ref_put(&ctx->refs);
+ io_req_task_complete(notif, locked);
}
-static inline void io_notif_complete(struct io_notif *notif)
+static inline void io_notif_complete(struct io_kiocb *notif)
+ __must_hold(¬if->ctx->uring_lock)
{
- __io_notif_complete_tw(¬if->task_work);
-}
+ bool locked = true;
-static void io_notif_complete_wq(struct work_struct *work)
-{
- struct io_notif *notif = container_of(work, struct io_notif, commit_work);
-
- io_notif_complete(notif);
+ __io_notif_complete_tw(notif, &locked);
}
static void io_uring_tx_zerocopy_callback(struct sk_buff *skb,
struct ubuf_info *uarg,
bool success)
{
- struct io_notif *notif = container_of(uarg, struct io_notif, uarg);
+ struct io_notif_data *nd = container_of(uarg, struct io_notif_data, uarg);
+ struct io_kiocb *notif = cmd_to_io_kiocb(nd);
- if (!refcount_dec_and_test(&uarg->refcnt))
- return;
-
- if (likely(notif->task)) {
- init_task_work(¬if->task_work, __io_notif_complete_tw);
- if (likely(!task_work_add(notif->task, ¬if->task_work,
- TWA_SIGNAL)))
- return;
- }
-
- INIT_WORK(¬if->commit_work, io_notif_complete_wq);
- queue_work(system_unbound_wq, ¬if->commit_work);
-}
-
-static void io_notif_splice_cached(struct io_ring_ctx *ctx)
- __must_hold(&ctx->uring_lock)
-{
- spin_lock(&ctx->completion_lock);
- list_splice_init(&ctx->notif_list_locked, &ctx->notif_list);
- ctx->notif_locked_nr = 0;
- spin_unlock(&ctx->completion_lock);
-}
-
-void io_notif_cache_purge(struct io_ring_ctx *ctx)
- __must_hold(&ctx->uring_lock)
-{
- io_notif_splice_cached(ctx);
-
- while (!list_empty(&ctx->notif_list)) {
- struct io_notif *notif = list_first_entry(&ctx->notif_list,
- struct io_notif, cache_node);
-
- list_del(¬if->cache_node);
- kfree(notif);
+ if (refcount_dec_and_test(&uarg->refcnt)) {
+ notif->io_task_work.func = __io_notif_complete_tw;
+ io_req_task_work_add(notif);
}
}
-static inline bool io_notif_has_cached(struct io_ring_ctx *ctx)
- __must_hold(&ctx->uring_lock)
-{
- if (likely(!list_empty(&ctx->notif_list)))
- return true;
- if (data_race(READ_ONCE(ctx->notif_locked_nr) <= IO_NOTIF_SPLICE_BATCH))
- return false;
- io_notif_splice_cached(ctx);
- return !list_empty(&ctx->notif_list);
-}
-
-struct io_notif *io_alloc_notif(struct io_ring_ctx *ctx,
+struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx,
struct io_notif_slot *slot)
__must_hold(&ctx->uring_lock)
{
- struct io_notif *notif;
+ struct io_kiocb *notif;
+ struct io_notif_data *nd;
- if (likely(io_notif_has_cached(ctx))) {
- notif = list_first_entry(&ctx->notif_list,
- struct io_notif, cache_node);
- list_del(¬if->cache_node);
- } else {
- notif = kzalloc(sizeof(*notif), GFP_ATOMIC | __GFP_ACCOUNT);
- if (!notif)
- return NULL;
- /* pre-initialise some fields */
- notif->ctx = ctx;
- notif->uarg.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
- notif->uarg.callback = io_uring_tx_zerocopy_callback;
- notif->account_pages = 0;
- }
+ if (unlikely(!io_alloc_req_refill(ctx)))
+ return NULL;
+ notif = io_alloc_req(ctx);
+ notif->opcode = IORING_OP_NOP;
+ notif->flags = 0;
+ notif->file = NULL;
+ notif->task = current;
+ io_get_task_refs(1);
+ notif->rsrc_node = NULL;
+ io_req_set_rsrc_node(notif, ctx, 0);
+ notif->cqe.user_data = slot->tag;
+ notif->cqe.flags = slot->seq++;
+ notif->cqe.res = 0;
- notif->seq = slot->seq++;
- notif->tag = slot->tag;
+ nd = io_notif_to_data(notif);
+ nd->account_pages = 0;
+ nd->uarg.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
+ nd->uarg.callback = io_uring_tx_zerocopy_callback;
/* master ref owned by io_notif_slot, will be dropped on flush */
- refcount_set(¬if->uarg.refcnt, 1);
- percpu_ref_get(&ctx->refs);
- notif->rsrc_node = ctx->rsrc_node;
- io_charge_rsrc_node(ctx);
+ refcount_set(&nd->uarg.refcnt, 1);
return notif;
}
void io_notif_slot_flush(struct io_notif_slot *slot)
__must_hold(&ctx->uring_lock)
{
- struct io_notif *notif = slot->notif;
+ struct io_kiocb *notif = slot->notif;
+ struct io_notif_data *nd = io_notif_to_data(notif);
slot->notif = NULL;
- if (WARN_ON_ONCE(in_interrupt()))
- return;
/* drop slot's master ref */
- if (refcount_dec_and_test(¬if->uarg.refcnt))
+ if (refcount_dec_and_test(&nd->uarg.refcnt))
io_notif_complete(notif);
}
@@ -156,18 +95,22 @@ __cold int io_notif_unregister(struct io_ring_ctx *ctx)
for (i = 0; i < ctx->nr_notif_slots; i++) {
struct io_notif_slot *slot = &ctx->notif_slots[i];
+ struct io_kiocb *notif = slot->notif;
+ struct io_notif_data *nd;
- if (!slot->notif)
+ if (!notif)
continue;
- if (WARN_ON_ONCE(slot->notif->task))
- slot->notif->task = NULL;
- io_notif_slot_flush(slot);
+ nd = io_kiocb_to_cmd(notif);
+ slot->notif = NULL;
+ if (!refcount_dec_and_test(&nd->uarg.refcnt))
+ continue;
+ notif->io_task_work.func = __io_notif_complete_tw;
+ io_req_task_work_add(notif);
}
kvfree(ctx->notif_slots);
ctx->notif_slots = NULL;
ctx->nr_notif_slots = 0;
- io_notif_cache_purge(ctx);
return 0;
}
@@ -180,6 +123,8 @@ __cold int io_notif_register(struct io_ring_ctx *ctx,
struct io_uring_notification_register reg;
unsigned i;
+ BUILD_BUG_ON(sizeof(struct io_notif_data) > 64);
+
if (ctx->nr_notif_slots)
return -EBUSY;
if (size != sizeof(reg))
diff --git a/io_uring/notif.h b/io_uring/notif.h
index d6f366b..0819304 100644
--- a/io_uring/notif.h
+++ b/io_uring/notif.h
@@ -10,27 +10,10 @@
#define IO_NOTIF_SPLICE_BATCH 32
#define IORING_MAX_NOTIF_SLOTS (1U << 10)
-struct io_notif {
+struct io_notif_data {
+ struct file *file;
struct ubuf_info uarg;
- struct io_ring_ctx *ctx;
- struct io_rsrc_node *rsrc_node;
-
- /* complete via tw if ->task is non-NULL, fallback to wq otherwise */
- struct task_struct *task;
-
- /* cqe->user_data, io_notif_slot::tag if not overridden */
- u64 tag;
- /* see struct io_notif_slot::seq */
- u32 seq;
- /* hook into ctx->notif_list and ctx->notif_list_locked */
- struct list_head cache_node;
-
unsigned long account_pages;
-
- union {
- struct callback_head task_work;
- struct work_struct commit_work;
- };
};
struct io_notif_slot {
@@ -39,7 +22,7 @@ struct io_notif_slot {
* time and keeps one reference to it. Flush releases the reference and
* lazily replaces it with a new notifier.
*/
- struct io_notif *notif;
+ struct io_kiocb *notif;
/*
* Default ->user_data for this slot notifiers CQEs
@@ -56,13 +39,17 @@ struct io_notif_slot {
int io_notif_register(struct io_ring_ctx *ctx,
void __user *arg, unsigned int size);
int io_notif_unregister(struct io_ring_ctx *ctx);
-void io_notif_cache_purge(struct io_ring_ctx *ctx);
void io_notif_slot_flush(struct io_notif_slot *slot);
-struct io_notif *io_alloc_notif(struct io_ring_ctx *ctx,
+struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx,
struct io_notif_slot *slot);
-static inline struct io_notif *io_get_notif(struct io_ring_ctx *ctx,
+static inline struct io_notif_data *io_notif_to_data(struct io_kiocb *notif)
+{
+ return io_kiocb_to_cmd(notif);
+}
+
+static inline struct io_kiocb *io_get_notif(struct io_ring_ctx *ctx,
struct io_notif_slot *slot)
{
if (!slot->notif)
@@ -83,16 +70,13 @@ static inline struct io_notif_slot *io_get_notif_slot(struct io_ring_ctx *ctx,
static inline void io_notif_slot_flush_submit(struct io_notif_slot *slot,
unsigned int issue_flags)
{
- if (!(issue_flags & IO_URING_F_UNLOCKED)) {
- slot->notif->task = current;
- io_get_task_refs(1);
- }
io_notif_slot_flush(slot);
}
-static inline int io_notif_account_mem(struct io_notif *notif, unsigned len)
+static inline int io_notif_account_mem(struct io_kiocb *notif, unsigned len)
{
struct io_ring_ctx *ctx = notif->ctx;
+ struct io_notif_data *nd = io_notif_to_data(notif);
unsigned nr_pages = (len >> PAGE_SHIFT) + 2;
int ret;
@@ -100,7 +84,7 @@ static inline int io_notif_account_mem(struct io_notif *notif, unsigned len)
ret = __io_account_mem(ctx->user, nr_pages);
if (ret)
return ret;
- notif->account_pages += nr_pages;
+ nd->account_pages += nr_pages;
}
return 0;
}
