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From: Pavel Begunkov <asml.silence@gmail.com>
To: Song Liu <songliubraving@fb.com>
Cc: "io-uring@vger.kernel.org" <io-uring@vger.kernel.org>,
	Networking <netdev@vger.kernel.org>,
	"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Jens Axboe <axboe@kernel.dk>, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>, Martin Lau <kafai@fb.com>,
	Yonghong Song <yhs@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Horst Schirmeier <horst.schirmeier@tu-dortmund.de>,
	"Franz-B . Tuneke" <franz-bernhard.tuneke@tu-dortmund.de>,
	Christian Dietrich <stettberger@dokucode.de>
Subject: Re: [PATCH 01/23] io_uring: shuffle rarely used ctx fields
Date: Thu, 20 May 2021 23:46:02 +0100	[thread overview]
Message-ID: <45a6f8f9-7abf-f513-e872-c346a682e373@gmail.com> (raw)
In-Reply-To: <0339DB35-27AC-4A50-B807-968C72ABB698@fb.com>

On 5/20/21 10:46 PM, Song Liu wrote:
>> On May 19, 2021, at 7:13 AM, Pavel Begunkov <asml.silence@gmail.com> wrote:
>> There is a bunch of scattered around ctx fields that are almost never
>> used, e.g. only on ring exit, plunge them to the end, better locality,
>> better aesthetically.
>>
>> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
>> ---
>> fs/io_uring.c | 36 +++++++++++++++++-------------------
>> 1 file changed, 17 insertions(+), 19 deletions(-)
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index 9ac5e278a91e..7e3410ce100a 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -367,9 +367,6 @@ struct io_ring_ctx {
>> 		unsigned		cached_cq_overflow;
>> 		unsigned long		sq_check_overflow;
>>
>> -		/* hashed buffered write serialization */
>> -		struct io_wq_hash	*hash_map;
>> -
>> 		struct list_head	defer_list;
>> 		struct list_head	timeout_list;
>> 		struct list_head	cq_overflow_list;
>> @@ -386,9 +383,6 @@ struct io_ring_ctx {
>>
>> 	struct io_rings	*rings;
>>
>> -	/* Only used for accounting purposes */
>> -	struct mm_struct	*mm_account;
>> -
>> 	const struct cred	*sq_creds;	/* cred used for __io_sq_thread() */
>> 	struct io_sq_data	*sq_data;	/* if using sq thread polling */
>>
>> @@ -409,14 +403,6 @@ struct io_ring_ctx {
>> 	unsigned		nr_user_bufs;
>> 	struct io_mapped_ubuf	**user_bufs;
>>
>> -	struct user_struct	*user;
>> -
>> -	struct completion	ref_comp;
>> -
>> -#if defined(CONFIG_UNIX)
>> -	struct socket		*ring_sock;
>> -#endif
>> -
>> 	struct xarray		io_buffers;
>>
>> 	struct xarray		personalities;
>> @@ -460,12 +446,24 @@ struct io_ring_ctx {
>>
>> 	struct io_restriction		restrictions;
>>
>> -	/* exit task_work */
>> -	struct callback_head		*exit_task_work;
>> -
>> 	/* Keep this last, we don't need it for the fast path */
>> -	struct work_struct		exit_work;
>> -	struct list_head		tctx_list;
>> +	struct {
> 
> Why do we need an anonymous struct here? For cache line alignment?
> Do we need ____cacheline_aligned_in_smp?

Rather as a visual hint considering that most of the field historically
are in structs (____cacheline_aligned_in_smp). Also preparing to
potentially splitting it out of the ctx struct as it grows big. 

First 2-3 patches are not strictly related to bpf and will go separately
earlier, just the set was based on.

>> +		#if defined(CONFIG_UNIX)
>> +			struct socket		*ring_sock;
>> +		#endif
>> +		/* hashed buffered write serialization */
>> +		struct io_wq_hash		*hash_map;
>> +
>> +		/* Only used for accounting purposes */
>> +		struct user_struct		*user;
>> +		struct mm_struct		*mm_account;
>> +
>> +		/* ctx exit and cancelation */
>> +		struct callback_head		*exit_task_work;
>> +		struct work_struct		exit_work;
>> +		struct list_head		tctx_list;
>> +		struct completion		ref_comp;
>> +	};
>> };
>>
>> struct io_uring_task {

-- 
Pavel Begunkov

  reply	other threads:[~2021-05-20 22:46 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-19 14:13 [RFC v2 00/23] io_uring BPF requests Pavel Begunkov
2021-05-19 14:13 ` [PATCH 01/23] io_uring: shuffle rarely used ctx fields Pavel Begunkov
2021-05-20 21:46   ` Song Liu
2021-05-20 22:46     ` Pavel Begunkov [this message]
2021-05-19 14:13 ` [PATCH 02/23] io_uring: localise fixed resources fields Pavel Begunkov
2021-05-19 14:13 ` [PATCH 03/23] io_uring: remove dependency on ring->sq/cq_entries Pavel Begunkov
2021-05-19 14:13 ` [PATCH 04/23] io_uring: deduce cq_mask from cq_entries Pavel Begunkov
2021-05-19 14:13 ` [PATCH 05/23] io_uring: kill cached_cq_overflow Pavel Begunkov
2021-05-19 14:13 ` [PATCH 06/23] io_uring: rename io_get_cqring Pavel Begunkov
2021-05-19 14:13 ` [PATCH 07/23] io_uring: extract struct for CQ Pavel Begunkov
2021-05-19 14:13 ` [PATCH 08/23] io_uring: internally pass CQ indexes Pavel Begunkov
2021-05-19 14:13 ` [PATCH 09/23] io_uring: extract cq size helper Pavel Begunkov
2021-05-19 14:13 ` [PATCH 10/23] io_uring: add support for multiple CQs Pavel Begunkov
2021-05-19 14:13 ` [PATCH 11/23] io_uring: enable mmap'ing additional CQs Pavel Begunkov
2021-05-19 14:13 ` [PATCH 12/23] bpf: add IOURING program type Pavel Begunkov
2021-05-20 23:34   ` Song Liu
2021-05-21  0:56     ` Pavel Begunkov
2021-05-19 14:13 ` [PATCH 13/23] io_uring: implement bpf prog registration Pavel Begunkov
2021-05-20 23:45   ` Song Liu
2021-05-21  0:43     ` Pavel Begunkov
2021-05-19 14:13 ` [PATCH 14/23] io_uring: add support for bpf requests Pavel Begunkov
2021-05-21  0:42   ` Pavel Begunkov
2021-05-19 14:13 ` [PATCH 15/23] io_uring: enable BPF to submit SQEs Pavel Begunkov
2021-05-21  0:06   ` Song Liu
2021-05-21  1:07   ` Alexei Starovoitov
2021-05-21  9:33     ` Pavel Begunkov
2021-05-19 14:13 ` [PATCH 16/23] io_uring: enable bpf to submit CQEs Pavel Begunkov
2021-05-19 14:13 ` [PATCH 17/23] io_uring: enable bpf to reap CQEs Pavel Begunkov
2021-05-19 14:13 ` [PATCH 18/23] libbpf: support io_uring Pavel Begunkov
2021-05-19 17:38   ` Andrii Nakryiko
2021-05-20  9:58     ` Pavel Begunkov
2021-05-20 17:23       ` Andrii Nakryiko
2021-05-19 14:13 ` [PATCH 19/23] io_uring: pass user_data to bpf executor Pavel Begunkov
2021-05-19 14:13 ` [PATCH 20/23] bpf: Add bpf_copy_to_user() helper Pavel Begunkov
2021-05-19 14:13 ` [PATCH 21/23] io_uring: wire bpf copy to user Pavel Begunkov
2021-05-19 14:13 ` [PATCH 22/23] io_uring: don't wait on CQ exclusively Pavel Begunkov
2021-05-19 14:13 ` [PATCH 23/23] io_uring: enable bpf reqs to wait for CQs Pavel Begunkov
2021-05-21  0:35 ` [RFC v2 00/23] io_uring BPF requests Song Liu
2021-05-21  0:58   ` Pavel Begunkov

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