From ab409402478462b5da007bfc46d165587c3adfc3 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Sat, 9 Oct 2021 23:14:41 +0100 Subject: io_uring: optimise rsrc referencing Apparently, percpu_ref_put/get() are expensive enough if done per request, get them in a batch and cache on the submission side to avoid getting it over and over again. Also, if we're completing under uring_lock, return refs back into the cache instead of perfcpu_ref_put(). Pretty similar to how we do tctx->cached_refs accounting, but fall back to normal putting when we already changed a rsrc node by the time of free. Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/b40d8c5bc77d3c9550df8a319117a374ac85f8f4.1633817310.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- fs/io_uring.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 49 insertions(+), 3 deletions(-) (limited to 'fs/io_uring.c') diff --git a/fs/io_uring.c b/fs/io_uring.c index 6486ebf31866..6859dae218f9 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -360,6 +360,7 @@ struct io_ring_ctx { * uring_lock, and updated through io_uring_register(2) */ struct io_rsrc_node *rsrc_node; + int rsrc_cached_refs; struct io_file_table file_table; unsigned nr_user_files; unsigned nr_user_bufs; @@ -1174,12 +1175,52 @@ static inline void io_req_set_refcount(struct io_kiocb *req) __io_req_set_refcount(req, 1); } +#define IO_RSRC_REF_BATCH 100 + +static inline void io_req_put_rsrc_locked(struct io_kiocb *req, + struct io_ring_ctx *ctx) + __must_hold(&ctx->uring_lock) +{ + struct percpu_ref *ref = req->fixed_rsrc_refs; + + if (ref) { + if (ref == &ctx->rsrc_node->refs) + ctx->rsrc_cached_refs++; + else + percpu_ref_put(ref); + } +} + +static inline void io_req_put_rsrc(struct io_kiocb *req, struct io_ring_ctx *ctx) +{ + if (req->fixed_rsrc_refs) + percpu_ref_put(req->fixed_rsrc_refs); +} + +static __cold void io_rsrc_refs_drop(struct io_ring_ctx *ctx) + __must_hold(&ctx->uring_lock) +{ + if (ctx->rsrc_cached_refs) { + percpu_ref_put_many(&ctx->rsrc_node->refs, ctx->rsrc_cached_refs); + ctx->rsrc_cached_refs = 0; + } +} + +static void io_rsrc_refs_refill(struct io_ring_ctx *ctx) + __must_hold(&ctx->uring_lock) +{ + ctx->rsrc_cached_refs += IO_RSRC_REF_BATCH; + percpu_ref_get_many(&ctx->rsrc_node->refs, IO_RSRC_REF_BATCH); +} + static inline void io_req_set_rsrc_node(struct io_kiocb *req, struct io_ring_ctx *ctx) { if (!req->fixed_rsrc_refs) { req->fixed_rsrc_refs = &ctx->rsrc_node->refs; - percpu_ref_get(req->fixed_rsrc_refs); + ctx->rsrc_cached_refs--; + if (unlikely(ctx->rsrc_cached_refs < 0)) + io_rsrc_refs_refill(ctx); } } @@ -1800,6 +1841,7 @@ static void io_req_complete_post(struct io_kiocb *req, s32 res, req->link = NULL; } } + io_req_put_rsrc(req, ctx); io_dismantle_req(req); io_put_task(req->task, 1); wq_list_add_head(&req->comp_list, &ctx->locked_free_list); @@ -1956,14 +1998,13 @@ static inline void io_dismantle_req(struct io_kiocb *req) io_clean_op(req); if (!(flags & REQ_F_FIXED_FILE)) io_put_file(req->file); - if (req->fixed_rsrc_refs) - percpu_ref_put(req->fixed_rsrc_refs); } static __cold void __io_free_req(struct io_kiocb *req) { struct io_ring_ctx *ctx = req->ctx; + io_req_put_rsrc(req, ctx); io_dismantle_req(req); io_put_task(req->task, 1); @@ -2271,6 +2312,7 @@ static void io_free_batch_list(struct io_ring_ctx *ctx, continue; } + io_req_put_rsrc_locked(req, ctx); io_queue_next(req); io_dismantle_req(req); @@ -7630,10 +7672,13 @@ static struct io_rsrc_node *io_rsrc_node_alloc(struct io_ring_ctx *ctx) static void io_rsrc_node_switch(struct io_ring_ctx *ctx, struct io_rsrc_data *data_to_kill) + __must_hold(&ctx->uring_lock) { WARN_ON_ONCE(!ctx->rsrc_backup_node); WARN_ON_ONCE(data_to_kill && !ctx->rsrc_node); + io_rsrc_refs_drop(ctx); + if (data_to_kill) { struct io_rsrc_node *rsrc_node = ctx->rsrc_node; @@ -9187,6 +9232,7 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx) ctx->mm_account = NULL; } + io_rsrc_refs_drop(ctx); /* __io_rsrc_put_work() may need uring_lock to progress, wait w/o it */ io_wait_rsrc_data(ctx->buf_data); io_wait_rsrc_data(ctx->file_data); -- cgit