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From:   Gabriel Krisman Bertazi <krisman@suse.de>
To:     Breno Leitao <leitao@debian.org>
Cc:     asml.silence@gmail.com, dylany@meta.com, axboe@kernel.dk,
        io-uring@vger.kernel.org, leit@fb.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] io_uring: Split io_issue_def struct
References: <20230112144411.2624698-1-leitao@debian.org>
        <20230112144411.2624698-2-leitao@debian.org>
Date:   Thu, 12 Jan 2023 17:35:22 -0300
In-Reply-To: <20230112144411.2624698-2-leitao@debian.org> (Breno Leitao's
        message of "Thu, 12 Jan 2023 06:44:11 -0800")
Message-ID: <87v8lbcwz9.fsf@suse.de>
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Breno Leitao <leitao@debian.org> writes:

> This patch removes some "cold" fields from `struct io_issue_def`.
>
> The plan is to keep only highly used fields into `struct io_issue_def`, so,
> it may be hot in the cache. The hot fields are basically all the bitfields
> and the callback functions for .issue and .prep.
>
> The other less frequently used fields are now located in a secondary and
> cold struct, called `io_cold_def`.
>
> This is the size for the structs:
>
> Before: io_issue_def = 56 bytes
> After: io_issue_def = 24 bytes; io_cold_def = 40 bytes

Does this change have an observable impact in run time? Did it show
a significant decrease of dcache misses?

>
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
>  io_uring/io_uring.c |  15 +-
>  io_uring/opdef.c    | 327 ++++++++++++++++++++++++++++++--------------
>  io_uring/opdef.h    |   9 +-
>  io_uring/rw.c       |   2 +-
>  4 files changed, 238 insertions(+), 115 deletions(-)
>
> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
> index ac7868ec9be2..0be66b026a7f 100644
> --- a/io_uring/io_uring.c
> +++ b/io_uring/io_uring.c
> @@ -980,7 +980,7 @@ void io_req_complete_post(struct io_kiocb *req, unsigned issue_flags)
>  void io_req_defer_failed(struct io_kiocb *req, s32 res)
>  	__must_hold(&ctx->uring_lock)
>  {
> -	const struct io_issue_def *def = &io_issue_defs[req->opcode];
> +	const struct io_cold_def *def = &io_cold_defs[req->opcode];
>  
>  	lockdep_assert_held(&req->ctx->uring_lock);
>  
> @@ -1708,8 +1708,8 @@ unsigned int io_file_get_flags(struct file *file)
>  
>  bool io_alloc_async_data(struct io_kiocb *req)
>  {
> -	WARN_ON_ONCE(!io_issue_defs[req->opcode].async_size);
> -	req->async_data = kmalloc(io_issue_defs[req->opcode].async_size, GFP_KERNEL);
> +	WARN_ON_ONCE(!io_cold_defs[req->opcode].async_size);
> +	req->async_data = kmalloc(io_cold_defs[req->opcode].async_size, GFP_KERNEL);
>  	if (req->async_data) {
>  		req->flags |= REQ_F_ASYNC_DATA;
>  		return false;
> @@ -1719,20 +1719,21 @@ bool io_alloc_async_data(struct io_kiocb *req)
>  
>  int io_req_prep_async(struct io_kiocb *req)
>  {
> +	const struct io_cold_def *cdef = &io_cold_defs[req->opcode];
>  	const struct io_issue_def *def = &io_issue_defs[req->opcode];
>  
>  	/* assign early for deferred execution for non-fixed file */
>  	if (def->needs_file && !(req->flags & REQ_F_FIXED_FILE))
>  		req->file = io_file_get_normal(req, req->cqe.fd);
> -	if (!def->prep_async)
> +	if (!cdef->prep_async)
>  		return 0;
>  	if (WARN_ON_ONCE(req_has_async_data(req)))
>  		return -EFAULT;
> -	if (!io_issue_defs[req->opcode].manual_alloc) {
> +	if (!def->manual_alloc) {
>  		if (io_alloc_async_data(req))
>  			return -EAGAIN;
>  	}
> -	return def->prep_async(req);
> +	return cdef->prep_async(req);
>  }
>  
>  static u32 io_get_sequence(struct io_kiocb *req)
> @@ -1801,7 +1802,7 @@ static void io_clean_op(struct io_kiocb *req)
>  	}
>  
>  	if (req->flags & REQ_F_NEED_CLEANUP) {
> -		const struct io_issue_def *def = &io_issue_defs[req->opcode];
> +		const struct io_cold_def *def = &io_cold_defs[req->opcode];
>  
>  		if (def->cleanup)
>  			def->cleanup(req);
> diff --git a/io_uring/opdef.c b/io_uring/opdef.c
> index 3c95e70a625e..5238ecd7af6a 100644
> --- a/io_uring/opdef.c
> +++ b/io_uring/opdef.c
> @@ -50,7 +50,6 @@ const struct io_issue_def io_issue_defs[] = {
>  	[IORING_OP_NOP] = {
>  		.audit_skip		= 1,
>  		.iopoll			= 1,
> -		.name			= "NOP",
>  		.prep			= io_nop_prep,
>  		.issue			= io_nop,
>  	},
> @@ -64,13 +63,8 @@ const struct io_issue_def io_issue_defs[] = {
>  		.ioprio			= 1,
>  		.iopoll			= 1,
>  		.iopoll_queue		= 1,
> -		.async_size		= sizeof(struct io_async_rw),
> -		.name			= "READV",
>  		.prep			= io_prep_rw,
>  		.issue			= io_read,
> -		.prep_async		= io_readv_prep_async,
> -		.cleanup		= io_readv_writev_cleanup,
> -		.fail			= io_rw_fail,
>  	},
>  	[IORING_OP_WRITEV] = {
>  		.needs_file		= 1,
> @@ -82,18 +76,12 @@ const struct io_issue_def io_issue_defs[] = {
>  		.ioprio			= 1,
>  		.iopoll			= 1,
>  		.iopoll_queue		= 1,
> -		.async_size		= sizeof(struct io_async_rw),
> -		.name			= "WRITEV",
>  		.prep			= io_prep_rw,
>  		.issue			= io_write,
> -		.prep_async		= io_writev_prep_async,
> -		.cleanup		= io_readv_writev_cleanup,
> -		.fail			= io_rw_fail,
>  	},
>  	[IORING_OP_FSYNC] = {
>  		.needs_file		= 1,
>  		.audit_skip		= 1,
> -		.name			= "FSYNC",
>  		.prep			= io_fsync_prep,
>  		.issue			= io_fsync,
>  	},
> @@ -106,11 +94,8 @@ const struct io_issue_def io_issue_defs[] = {
>  		.ioprio			= 1,
>  		.iopoll			= 1,
>  		.iopoll_queue		= 1,
> -		.async_size		= sizeof(struct io_async_rw),
> -		.name			= "READ_FIXED",
>  		.prep			= io_prep_rw,
>  		.issue			= io_read,
> -		.fail			= io_rw_fail,
>  	},
>  	[IORING_OP_WRITE_FIXED] = {
>  		.needs_file		= 1,
> @@ -122,30 +107,24 @@ const struct io_issue_def io_issue_defs[] = {
>  		.ioprio			= 1,
>  		.iopoll			= 1,
>  		.iopoll_queue		= 1,
> -		.async_size		= sizeof(struct io_async_rw),
> -		.name			= "WRITE_FIXED",
>  		.prep			= io_prep_rw,
>  		.issue			= io_write,
> -		.fail			= io_rw_fail,
>  	},
>  	[IORING_OP_POLL_ADD] = {
>  		.needs_file		= 1,
>  		.unbound_nonreg_file	= 1,
>  		.audit_skip		= 1,
> -		.name			= "POLL_ADD",
>  		.prep			= io_poll_add_prep,
>  		.issue			= io_poll_add,
>  	},
>  	[IORING_OP_POLL_REMOVE] = {
>  		.audit_skip		= 1,
> -		.name			= "POLL_REMOVE",
>  		.prep			= io_poll_remove_prep,
>  		.issue			= io_poll_remove,
>  	},
>  	[IORING_OP_SYNC_FILE_RANGE] = {
>  		.needs_file		= 1,
>  		.audit_skip		= 1,
> -		.name			= "SYNC_FILE_RANGE",
>  		.prep			= io_sfr_prep,
>  		.issue			= io_sync_file_range,
>  	},
> @@ -155,14 +134,9 @@ const struct io_issue_def io_issue_defs[] = {
>  		.pollout		= 1,
>  		.ioprio			= 1,
>  		.manual_alloc		= 1,
> -		.name			= "SENDMSG",
>  #if defined(CONFIG_NET)
> -		.async_size		= sizeof(struct io_async_msghdr),
>  		.prep			= io_sendmsg_prep,
>  		.issue			= io_sendmsg,
> -		.prep_async		= io_sendmsg_prep_async,
> -		.cleanup		= io_sendmsg_recvmsg_cleanup,
> -		.fail			= io_sendrecv_fail,
>  #else
>  		.prep			= io_eopnotsupp_prep,
>  #endif
> @@ -174,29 +148,21 @@ const struct io_issue_def io_issue_defs[] = {
>  		.buffer_select		= 1,
>  		.ioprio			= 1,
>  		.manual_alloc		= 1,
> -		.name			= "RECVMSG",
>  #if defined(CONFIG_NET)
> -		.async_size		= sizeof(struct io_async_msghdr),
>  		.prep			= io_recvmsg_prep,
>  		.issue			= io_recvmsg,
> -		.prep_async		= io_recvmsg_prep_async,
> -		.cleanup		= io_sendmsg_recvmsg_cleanup,
> -		.fail			= io_sendrecv_fail,
>  #else
>  		.prep			= io_eopnotsupp_prep,
>  #endif
>  	},
>  	[IORING_OP_TIMEOUT] = {
>  		.audit_skip		= 1,
> -		.async_size		= sizeof(struct io_timeout_data),
> -		.name			= "TIMEOUT",
>  		.prep			= io_timeout_prep,
>  		.issue			= io_timeout,
>  	},
>  	[IORING_OP_TIMEOUT_REMOVE] = {
>  		/* used by timeout updates' prep() */
>  		.audit_skip		= 1,
> -		.name			= "TIMEOUT_REMOVE",
>  		.prep			= io_timeout_remove_prep,
>  		.issue			= io_timeout_remove,
>  	},
> @@ -206,7 +172,6 @@ const struct io_issue_def io_issue_defs[] = {
>  		.pollin			= 1,
>  		.poll_exclusive		= 1,
>  		.ioprio			= 1,	/* used for flags */
> -		.name			= "ACCEPT",
>  #if defined(CONFIG_NET)
>  		.prep			= io_accept_prep,
>  		.issue			= io_accept,
> @@ -216,14 +181,11 @@ const struct io_issue_def io_issue_defs[] = {
>  	},
>  	[IORING_OP_ASYNC_CANCEL] = {
>  		.audit_skip		= 1,
> -		.name			= "ASYNC_CANCEL",
>  		.prep			= io_async_cancel_prep,
>  		.issue			= io_async_cancel,
>  	},
>  	[IORING_OP_LINK_TIMEOUT] = {
>  		.audit_skip		= 1,
> -		.async_size		= sizeof(struct io_timeout_data),
> -		.name			= "LINK_TIMEOUT",
>  		.prep			= io_link_timeout_prep,
>  		.issue			= io_no_issue,
>  	},
> @@ -231,46 +193,36 @@ const struct io_issue_def io_issue_defs[] = {
>  		.needs_file		= 1,
>  		.unbound_nonreg_file	= 1,
>  		.pollout		= 1,
> -		.name			= "CONNECT",
>  #if defined(CONFIG_NET)
> -		.async_size		= sizeof(struct io_async_connect),
>  		.prep			= io_connect_prep,
>  		.issue			= io_connect,
> -		.prep_async		= io_connect_prep_async,
>  #else
>  		.prep			= io_eopnotsupp_prep,
>  #endif
>  	},
>  	[IORING_OP_FALLOCATE] = {
>  		.needs_file		= 1,
> -		.name			= "FALLOCATE",
>  		.prep			= io_fallocate_prep,
>  		.issue			= io_fallocate,
>  	},
>  	[IORING_OP_OPENAT] = {
> -		.name			= "OPENAT",
>  		.prep			= io_openat_prep,
>  		.issue			= io_openat,
> -		.cleanup		= io_open_cleanup,
>  	},
>  	[IORING_OP_CLOSE] = {
> -		.name			= "CLOSE",
>  		.prep			= io_close_prep,
>  		.issue			= io_close,
>  	},
>  	[IORING_OP_FILES_UPDATE] = {
>  		.audit_skip		= 1,
>  		.iopoll			= 1,
> -		.name			= "FILES_UPDATE",
>  		.prep			= io_files_update_prep,
>  		.issue			= io_files_update,
>  	},
>  	[IORING_OP_STATX] = {
>  		.audit_skip		= 1,
> -		.name			= "STATX",
>  		.prep			= io_statx_prep,
>  		.issue			= io_statx,
> -		.cleanup		= io_statx_cleanup,
>  	},
>  	[IORING_OP_READ] = {
>  		.needs_file		= 1,
> @@ -282,11 +234,8 @@ const struct io_issue_def io_issue_defs[] = {
>  		.ioprio			= 1,
>  		.iopoll			= 1,
>  		.iopoll_queue		= 1,
> -		.async_size		= sizeof(struct io_async_rw),
> -		.name			= "READ",
>  		.prep			= io_prep_rw,
>  		.issue			= io_read,
> -		.fail			= io_rw_fail,
>  	},
>  	[IORING_OP_WRITE] = {
>  		.needs_file		= 1,
> @@ -298,21 +247,16 @@ const struct io_issue_def io_issue_defs[] = {
>  		.ioprio			= 1,
>  		.iopoll			= 1,
>  		.iopoll_queue		= 1,
> -		.async_size		= sizeof(struct io_async_rw),
> -		.name			= "WRITE",
>  		.prep			= io_prep_rw,
>  		.issue			= io_write,
> -		.fail			= io_rw_fail,
>  	},
>  	[IORING_OP_FADVISE] = {
>  		.needs_file		= 1,
>  		.audit_skip		= 1,
> -		.name			= "FADVISE",
>  		.prep			= io_fadvise_prep,
>  		.issue			= io_fadvise,
>  	},
>  	[IORING_OP_MADVISE] = {
> -		.name			= "MADVISE",
>  		.prep			= io_madvise_prep,
>  		.issue			= io_madvise,
>  	},
> @@ -323,13 +267,9 @@ const struct io_issue_def io_issue_defs[] = {
>  		.audit_skip		= 1,
>  		.ioprio			= 1,
>  		.manual_alloc		= 1,
> -		.name			= "SEND",
>  #if defined(CONFIG_NET)
> -		.async_size		= sizeof(struct io_async_msghdr),
>  		.prep			= io_sendmsg_prep,
>  		.issue			= io_send,
> -		.fail			= io_sendrecv_fail,
> -		.prep_async		= io_send_prep_async,
>  #else
>  		.prep			= io_eopnotsupp_prep,
>  #endif
> @@ -341,25 +281,20 @@ const struct io_issue_def io_issue_defs[] = {
>  		.buffer_select		= 1,
>  		.audit_skip		= 1,
>  		.ioprio			= 1,
> -		.name			= "RECV",
>  #if defined(CONFIG_NET)
>  		.prep			= io_recvmsg_prep,
>  		.issue			= io_recv,
> -		.fail			= io_sendrecv_fail,
>  #else
>  		.prep			= io_eopnotsupp_prep,
>  #endif
>  	},
>  	[IORING_OP_OPENAT2] = {
> -		.name			= "OPENAT2",
>  		.prep			= io_openat2_prep,
>  		.issue			= io_openat2,
> -		.cleanup		= io_open_cleanup,
>  	},
>  	[IORING_OP_EPOLL_CTL] = {
>  		.unbound_nonreg_file	= 1,
>  		.audit_skip		= 1,
> -		.name			= "EPOLL",
>  #if defined(CONFIG_EPOLL)
>  		.prep			= io_epoll_ctl_prep,
>  		.issue			= io_epoll_ctl,
> @@ -372,21 +307,18 @@ const struct io_issue_def io_issue_defs[] = {
>  		.hash_reg_file		= 1,
>  		.unbound_nonreg_file	= 1,
>  		.audit_skip		= 1,
> -		.name			= "SPLICE",
>  		.prep			= io_splice_prep,
>  		.issue			= io_splice,
>  	},
>  	[IORING_OP_PROVIDE_BUFFERS] = {
>  		.audit_skip		= 1,
>  		.iopoll			= 1,
> -		.name			= "PROVIDE_BUFFERS",
>  		.prep			= io_provide_buffers_prep,
>  		.issue			= io_provide_buffers,
>  	},
>  	[IORING_OP_REMOVE_BUFFERS] = {
>  		.audit_skip		= 1,
>  		.iopoll			= 1,
> -		.name			= "REMOVE_BUFFERS",
>  		.prep			= io_remove_buffers_prep,
>  		.issue			= io_remove_buffers,
>  	},
> @@ -395,13 +327,11 @@ const struct io_issue_def io_issue_defs[] = {
>  		.hash_reg_file		= 1,
>  		.unbound_nonreg_file	= 1,
>  		.audit_skip		= 1,
> -		.name			= "TEE",
>  		.prep			= io_tee_prep,
>  		.issue			= io_tee,
>  	},
>  	[IORING_OP_SHUTDOWN] = {
>  		.needs_file		= 1,
> -		.name			= "SHUTDOWN",
>  #if defined(CONFIG_NET)
>  		.prep			= io_shutdown_prep,
>  		.issue			= io_shutdown,
> @@ -410,72 +340,51 @@ const struct io_issue_def io_issue_defs[] = {
>  #endif
>  	},
>  	[IORING_OP_RENAMEAT] = {
> -		.name			= "RENAMEAT",
>  		.prep			= io_renameat_prep,
>  		.issue			= io_renameat,
> -		.cleanup		= io_renameat_cleanup,
>  	},
>  	[IORING_OP_UNLINKAT] = {
> -		.name			= "UNLINKAT",
>  		.prep			= io_unlinkat_prep,
>  		.issue			= io_unlinkat,
> -		.cleanup		= io_unlinkat_cleanup,
>  	},
>  	[IORING_OP_MKDIRAT] = {
> -		.name			= "MKDIRAT",
>  		.prep			= io_mkdirat_prep,
>  		.issue			= io_mkdirat,
> -		.cleanup		= io_mkdirat_cleanup,
>  	},
>  	[IORING_OP_SYMLINKAT] = {
> -		.name			= "SYMLINKAT",
>  		.prep			= io_symlinkat_prep,
>  		.issue			= io_symlinkat,
> -		.cleanup		= io_link_cleanup,
>  	},
>  	[IORING_OP_LINKAT] = {
> -		.name			= "LINKAT",
>  		.prep			= io_linkat_prep,
>  		.issue			= io_linkat,
> -		.cleanup		= io_link_cleanup,
>  	},
>  	[IORING_OP_MSG_RING] = {
>  		.needs_file		= 1,
>  		.iopoll			= 1,
> -		.name			= "MSG_RING",
>  		.prep			= io_msg_ring_prep,
>  		.issue			= io_msg_ring,
> -		.cleanup		= io_msg_ring_cleanup,
>  	},
>  	[IORING_OP_FSETXATTR] = {
>  		.needs_file = 1,
> -		.name			= "FSETXATTR",
>  		.prep			= io_fsetxattr_prep,
>  		.issue			= io_fsetxattr,
> -		.cleanup		= io_xattr_cleanup,
>  	},
>  	[IORING_OP_SETXATTR] = {
> -		.name			= "SETXATTR",
>  		.prep			= io_setxattr_prep,
>  		.issue			= io_setxattr,
> -		.cleanup		= io_xattr_cleanup,
>  	},
>  	[IORING_OP_FGETXATTR] = {
>  		.needs_file = 1,
> -		.name			= "FGETXATTR",
>  		.prep			= io_fgetxattr_prep,
>  		.issue			= io_fgetxattr,
> -		.cleanup		= io_xattr_cleanup,
>  	},
>  	[IORING_OP_GETXATTR] = {
> -		.name			= "GETXATTR",
>  		.prep			= io_getxattr_prep,
>  		.issue			= io_getxattr,
> -		.cleanup		= io_xattr_cleanup,
>  	},
>  	[IORING_OP_SOCKET] = {
>  		.audit_skip		= 1,
> -		.name			= "SOCKET",
>  #if defined(CONFIG_NET)
>  		.prep			= io_socket_prep,
>  		.issue			= io_socket,
> @@ -486,16 +395,12 @@ const struct io_issue_def io_issue_defs[] = {
>  	[IORING_OP_URING_CMD] = {
>  		.needs_file		= 1,
>  		.plug			= 1,
> -		.name			= "URING_CMD",
>  		.iopoll			= 1,
>  		.iopoll_queue		= 1,
> -		.async_size		= uring_cmd_pdu_size(1),
>  		.prep			= io_uring_cmd_prep,
>  		.issue			= io_uring_cmd,
> -		.prep_async		= io_uring_cmd_prep_async,
>  	},
>  	[IORING_OP_SEND_ZC] = {
> -		.name			= "SEND_ZC",
>  		.needs_file		= 1,
>  		.unbound_nonreg_file	= 1,
>  		.pollout		= 1,
> @@ -503,32 +408,243 @@ const struct io_issue_def io_issue_defs[] = {
>  		.ioprio			= 1,
>  		.manual_alloc		= 1,
>  #if defined(CONFIG_NET)
> -		.async_size		= sizeof(struct io_async_msghdr),
>  		.prep			= io_send_zc_prep,
>  		.issue			= io_send_zc,
> -		.prep_async		= io_send_prep_async,
> -		.cleanup		= io_send_zc_cleanup,
> -		.fail			= io_sendrecv_fail,
>  #else
>  		.prep			= io_eopnotsupp_prep,
>  #endif
>  	},
>  	[IORING_OP_SENDMSG_ZC] = {
> -		.name			= "SENDMSG_ZC",
>  		.needs_file		= 1,
>  		.unbound_nonreg_file	= 1,
>  		.pollout		= 1,
>  		.ioprio			= 1,
>  		.manual_alloc		= 1,
>  #if defined(CONFIG_NET)
> -		.async_size		= sizeof(struct io_async_msghdr),
>  		.prep			= io_send_zc_prep,
>  		.issue			= io_sendmsg_zc,
> +#else
> +		.prep			= io_eopnotsupp_prep,
> +#endif
> +	},
> +};
> +
> +
> +const struct io_cold_def io_cold_defs[] = {
> +	[IORING_OP_NOP] = {
> +		.name			= "NOP",
> +	},
> +	[IORING_OP_READV] = {
> +		.async_size		= sizeof(struct io_async_rw),
> +		.name			= "READV",
> +		.prep_async		= io_readv_prep_async,
> +		.cleanup		= io_readv_writev_cleanup,
> +		.fail			= io_rw_fail,
> +	},
> +	[IORING_OP_WRITEV] = {
> +		.async_size		= sizeof(struct io_async_rw),
> +		.name			= "WRITEV",
> +		.prep_async		= io_writev_prep_async,
> +		.cleanup		= io_readv_writev_cleanup,
> +		.fail			= io_rw_fail,
> +	},
> +	[IORING_OP_FSYNC] = {
> +		.name			= "FSYNC",
> +	},
> +	[IORING_OP_READ_FIXED] = {
> +		.async_size		= sizeof(struct io_async_rw),
> +		.name			= "READ_FIXED",
> +		.fail			= io_rw_fail,
> +	},
> +	[IORING_OP_WRITE_FIXED] = {
> +		.async_size		= sizeof(struct io_async_rw),
> +		.name			= "WRITE_FIXED",
> +		.fail			= io_rw_fail,
> +	},
> +	[IORING_OP_POLL_ADD] = {
> +		.name			= "POLL_ADD",
> +	},
> +	[IORING_OP_POLL_REMOVE] = {
> +		.name			= "POLL_REMOVE",
> +	},
> +	[IORING_OP_SYNC_FILE_RANGE] = {
> +		.name			= "SYNC_FILE_RANGE",
> +	},
> +	[IORING_OP_SENDMSG] = {
> +		.name			= "SENDMSG",
> +#if defined(CONFIG_NET)
> +		.async_size		= sizeof(struct io_async_msghdr),
> +		.prep_async		= io_sendmsg_prep_async,
> +		.cleanup		= io_sendmsg_recvmsg_cleanup,
> +		.fail			= io_sendrecv_fail,
> +#endif
> +	},
> +	[IORING_OP_RECVMSG] = {
> +		.name			= "RECVMSG",
> +#if defined(CONFIG_NET)
> +		.async_size		= sizeof(struct io_async_msghdr),
> +		.prep_async		= io_recvmsg_prep_async,
> +		.cleanup		= io_sendmsg_recvmsg_cleanup,
> +		.fail			= io_sendrecv_fail,
> +#endif
> +	},
> +	[IORING_OP_TIMEOUT] = {
> +		.async_size		= sizeof(struct io_timeout_data),
> +		.name			= "TIMEOUT",
> +	},
> +	[IORING_OP_TIMEOUT_REMOVE] = {
> +		.name			= "TIMEOUT_REMOVE",
> +	},
> +	[IORING_OP_ACCEPT] = {
> +		.name			= "ACCEPT",
> +	},
> +	[IORING_OP_ASYNC_CANCEL] = {
> +		.name			= "ASYNC_CANCEL",
> +	},
> +	[IORING_OP_LINK_TIMEOUT] = {
> +		.async_size		= sizeof(struct io_timeout_data),
> +		.name			= "LINK_TIMEOUT",
> +	},
> +	[IORING_OP_CONNECT] = {
> +		.name			= "CONNECT",
> +#if defined(CONFIG_NET)
> +		.async_size		= sizeof(struct io_async_connect),
> +		.prep_async		= io_connect_prep_async,
> +#endif
> +	},
> +	[IORING_OP_FALLOCATE] = {
> +		.name			= "FALLOCATE",
> +	},
> +	[IORING_OP_OPENAT] = {
> +		.name			= "OPENAT",
> +		.cleanup		= io_open_cleanup,
> +	},
> +	[IORING_OP_CLOSE] = {
> +		.name			= "CLOSE",
> +	},
> +	[IORING_OP_FILES_UPDATE] = {
> +		.name			= "FILES_UPDATE",
> +	},
> +	[IORING_OP_STATX] = {
> +		.name			= "STATX",
> +		.cleanup		= io_statx_cleanup,
> +	},
> +	[IORING_OP_READ] = {
> +		.async_size		= sizeof(struct io_async_rw),
> +		.name			= "READ",
> +		.fail			= io_rw_fail,
> +	},
> +	[IORING_OP_WRITE] = {
> +		.async_size		= sizeof(struct io_async_rw),
> +		.name			= "WRITE",
> +		.fail			= io_rw_fail,
> +	},
> +	[IORING_OP_FADVISE] = {
> +		.name			= "FADVISE",
> +	},
> +	[IORING_OP_MADVISE] = {
> +		.name			= "MADVISE",
> +	},
> +	[IORING_OP_SEND] = {
> +		.name			= "SEND",
> +#if defined(CONFIG_NET)
> +		.async_size		= sizeof(struct io_async_msghdr),
> +		.fail			= io_sendrecv_fail,
> +		.prep_async		= io_send_prep_async,
> +#endif
> +	},
> +	[IORING_OP_RECV] = {
> +		.name			= "RECV",
> +#if defined(CONFIG_NET)
> +		.fail			= io_sendrecv_fail,
> +#endif
> +	},
> +	[IORING_OP_OPENAT2] = {
> +		.name			= "OPENAT2",
> +		.cleanup		= io_open_cleanup,
> +	},
> +	[IORING_OP_EPOLL_CTL] = {
> +		.name			= "EPOLL",
> +	},
> +	[IORING_OP_SPLICE] = {
> +		.name			= "SPLICE",
> +	},
> +	[IORING_OP_PROVIDE_BUFFERS] = {
> +		.name			= "PROVIDE_BUFFERS",
> +	},
> +	[IORING_OP_REMOVE_BUFFERS] = {
> +		.name			= "REMOVE_BUFFERS",
> +	},
> +	[IORING_OP_TEE] = {
> +		.name			= "TEE",
> +	},
> +	[IORING_OP_SHUTDOWN] = {
> +		.name			= "SHUTDOWN",
> +	},
> +	[IORING_OP_RENAMEAT] = {
> +		.name			= "RENAMEAT",
> +		.cleanup		= io_renameat_cleanup,
> +	},
> +	[IORING_OP_UNLINKAT] = {
> +		.name			= "UNLINKAT",
> +		.cleanup		= io_unlinkat_cleanup,
> +	},
> +	[IORING_OP_MKDIRAT] = {
> +		.name			= "MKDIRAT",
> +		.cleanup		= io_mkdirat_cleanup,
> +	},
> +	[IORING_OP_SYMLINKAT] = {
> +		.name			= "SYMLINKAT",
> +		.cleanup		= io_link_cleanup,
> +	},
> +	[IORING_OP_LINKAT] = {
> +		.name			= "LINKAT",
> +		.cleanup		= io_link_cleanup,
> +	},
> +	[IORING_OP_MSG_RING] = {
> +		.name			= "MSG_RING",
> +		.cleanup		= io_msg_ring_cleanup,
> +	},
> +	[IORING_OP_FSETXATTR] = {
> +		.name			= "FSETXATTR",
> +		.cleanup		= io_xattr_cleanup,
> +	},
> +	[IORING_OP_SETXATTR] = {
> +		.name			= "SETXATTR",
> +		.cleanup		= io_xattr_cleanup,
> +	},
> +	[IORING_OP_FGETXATTR] = {
> +		.name			= "FGETXATTR",
> +		.cleanup		= io_xattr_cleanup,
> +	},
> +	[IORING_OP_GETXATTR] = {
> +		.name			= "GETXATTR",
> +		.cleanup		= io_xattr_cleanup,
> +	},
> +	[IORING_OP_SOCKET] = {
> +		.name			= "SOCKET",
> +	},
> +	[IORING_OP_URING_CMD] = {
> +		.name			= "URING_CMD",
> +		.async_size		= uring_cmd_pdu_size(1),
> +		.prep_async		= io_uring_cmd_prep_async,
> +	},
> +	[IORING_OP_SEND_ZC] = {
> +		.name			= "SEND_ZC",
> +#if defined(CONFIG_NET)
> +		.async_size		= sizeof(struct io_async_msghdr),
> +		.prep_async		= io_send_prep_async,
> +		.cleanup		= io_send_zc_cleanup,
> +		.fail			= io_sendrecv_fail,
> +#endif
> +	},
> +	[IORING_OP_SENDMSG_ZC] = {
> +		.name			= "SENDMSG_ZC",
> +#if defined(CONFIG_NET)
> +		.async_size		= sizeof(struct io_async_msghdr),
>  		.prep_async		= io_sendmsg_prep_async,
>  		.cleanup		= io_send_zc_cleanup,
>  		.fail			= io_sendrecv_fail,
> -#else
> -		.prep			= io_eopnotsupp_prep,
>  #endif
>  	},
>  };
> @@ -536,7 +652,7 @@ const struct io_issue_def io_issue_defs[] = {
>  const char *io_uring_get_opcode(u8 opcode)
>  {
>  	if (opcode < IORING_OP_LAST)
> -		return io_issue_defs[opcode].name;
> +		return io_cold_defs[opcode].name;
>  	return "INVALID";
>  }
>  
> @@ -544,12 +660,13 @@ void __init io_uring_optable_init(void)
>  {
>  	int i;
>  
> +	BUILD_BUG_ON(ARRAY_SIZE(io_cold_defs) != IORING_OP_LAST);
>  	BUILD_BUG_ON(ARRAY_SIZE(io_issue_defs) != IORING_OP_LAST);
>  
>  	for (i = 0; i < ARRAY_SIZE(io_issue_defs); i++) {
>  		BUG_ON(!io_issue_defs[i].prep);
>  		if (io_issue_defs[i].prep != io_eopnotsupp_prep)
>  			BUG_ON(!io_issue_defs[i].issue);
> -		WARN_ON_ONCE(!io_issue_defs[i].name);
> +		WARN_ON_ONCE(!io_cold_defs[i].name);
>  	}
>  }
> diff --git a/io_uring/opdef.h b/io_uring/opdef.h
> index d718e2ab1ff7..c22c8696e749 100644
> --- a/io_uring/opdef.h
> +++ b/io_uring/opdef.h
> @@ -29,19 +29,24 @@ struct io_issue_def {
>  	unsigned		iopoll_queue : 1;
>  	/* opcode specific path will handle ->async_data allocation if needed */
>  	unsigned		manual_alloc : 1;
> +
> +	int (*issue)(struct io_kiocb *, unsigned int);
> +	int (*prep)(struct io_kiocb *, const struct io_uring_sqe *);
> +};
> +
> +struct io_cold_def {
>  	/* size of async data needed, if any */
>  	unsigned short		async_size;
>  
>  	const char		*name;
>  
> -	int (*prep)(struct io_kiocb *, const struct io_uring_sqe *);
> -	int (*issue)(struct io_kiocb *, unsigned int);
>  	int (*prep_async)(struct io_kiocb *);
>  	void (*cleanup)(struct io_kiocb *);
>  	void (*fail)(struct io_kiocb *);
>  };
>  
>  extern const struct io_issue_def io_issue_defs[];
> +extern const struct io_cold_def io_cold_defs[];
>  
>  void io_uring_optable_init(void);
>  #endif
> diff --git a/io_uring/rw.c b/io_uring/rw.c
> index 54b44b9b736c..a8a2eb7ee27a 100644
> --- a/io_uring/rw.c
> +++ b/io_uring/rw.c
> @@ -516,7 +516,7 @@ static void io_req_map_rw(struct io_kiocb *req, const struct iovec *iovec,
>  static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec,
>  			     struct io_rw_state *s, bool force)
>  {
> -	if (!force && !io_issue_defs[req->opcode].prep_async)
> +	if (!force && !io_cold_defs[req->opcode].prep_async)
>  		return 0;
>  	if (!req_has_async_data(req)) {
>  		struct io_async_rw *iorw;

-- 
Gabriel Krisman Bertazi