From eb4a299b2f95437af6183946c2a2e850621cefdb Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Tue, 12 Jul 2022 21:52:39 +0100 Subject: io_uring: cache struct io_notif kmalloc'ing struct io_notif is too expensive when done frequently, cache them as many other resources in io_uring. Keep two list, the first one is from where we're getting notifiers, it's protected by ->uring_lock. The second is protected by ->completion_lock, to which we queue released notifiers. Then we splice one list into another when needed. Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/9dec18f7fcbab9f4bd40b96e5ae158b119945230.1657643355.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- io_uring/io_uring.c | 3 +++ io_uring/notif.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++------- io_uring/notif.h | 5 +++++ 3 files changed, 58 insertions(+), 7 deletions(-) (limited to 'io_uring') diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 65ac407dd74e..20e65d45ca1c 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -321,6 +321,8 @@ 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); @@ -2493,6 +2495,7 @@ 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/notif.c b/io_uring/notif.c index 6ee948af6a49..b257db2120b4 100644 --- a/io_uring/notif.c +++ b/io_uring/notif.c @@ -15,10 +15,12 @@ static void __io_notif_complete_tw(struct callback_head *cb) 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); percpu_ref_put(&ctx->refs); - kfree(notif); } static inline void io_notif_complete(struct io_notif *notif) @@ -45,21 +47,62 @@ static void io_uring_tx_zerocopy_callback(struct sk_buff *skb, 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); + } +} + +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_notif_slot *slot) __must_hold(&ctx->uring_lock) { struct io_notif *notif; - notif = kzalloc(sizeof(*notif), GFP_ATOMIC | __GFP_ACCOUNT); - if (!notif) - return NULL; + 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->seq = slot->seq++; notif->tag = slot->tag; - notif->ctx = ctx; - notif->uarg.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN; - notif->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); diff --git a/io_uring/notif.h b/io_uring/notif.h index 3d7a1d242e17..b23c9c0515bb 100644 --- a/io_uring/notif.h +++ b/io_uring/notif.h @@ -5,6 +5,8 @@ #include #include +#define IO_NOTIF_SPLICE_BATCH 32 + struct io_notif { struct ubuf_info uarg; struct io_ring_ctx *ctx; @@ -13,6 +15,8 @@ struct io_notif { 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; union { struct callback_head task_work; @@ -41,6 +45,7 @@ struct io_notif_slot { }; int io_notif_unregister(struct io_ring_ctx *ctx); +void io_notif_cache_purge(struct io_ring_ctx *ctx); struct io_notif *io_alloc_notif(struct io_ring_ctx *ctx, struct io_notif_slot *slot); -- cgit v1.2.3