linux-kernel - Re: [PATCH v2 2/2] io_uring: Create define to modify a SQPOLL parameter

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Message-ID: <b8b77ef8-6908-6446-5245-5dbd8fa7cfd7@gmail.com>
Date:   Wed, 23 Jun 2021 23:14:29 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Olivier Langlois <olivier@...llion01.com>,
        Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] io_uring: Create define to modify a SQPOLL
 parameter

On 6/23/21 7:50 PM, Olivier Langlois wrote:
> The magic number used to cap the number of entries extracted from an
> io_uring instance SQ before moving to the other instances is an
> interesting parameter to experiment with.
> 
> A define has been created to make it easy to change its value from a
> single location.

It's better to send fixes separately from other improvements,
because the process a bit different for them, go into different
branches and so on.

Jens, any chance you can pick as is (at least 1/2)?

Reviewed-by: Pavel Begunkov <asml.silence@...il.com>
 
> Signed-off-by: Olivier Langlois <olivier@...llion01.com>
> ---
>  fs/io_uring.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 7c545fa66f31..e7997f9bf879 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -89,6 +89,7 @@
>  
>  #define IORING_MAX_ENTRIES	32768
>  #define IORING_MAX_CQ_ENTRIES	(2 * IORING_MAX_ENTRIES)
> +#define IORING_SQPOLL_CAP_ENTRIES_VALUE 8
>  
>  /*
>   * Shift of 9 is 512 entries, or exactly one page on 64-bit archs
> @@ -6797,8 +6798,8 @@ static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)
>  
>  	to_submit = io_sqring_entries(ctx);
>  	/* if we're handling multiple rings, cap submit size for fairness */
> -	if (cap_entries && to_submit > 8)
> -		to_submit = 8;
> +	if (cap_entries && to_submit > IORING_SQPOLL_CAP_ENTRIES_VALUE)
> +		to_submit = IORING_SQPOLL_CAP_ENTRIES_VALUE;
>  
>  	if (!list_empty(&ctx->iopoll_list) || to_submit) {
>  		unsigned nr_events = 0;
> 

-- 
Pavel Begunkov