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/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))
