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From: Jens Axboe <[email protected]>
To: Xiaoguang Wang <[email protected]>,
	[email protected]
Cc: [email protected]
Subject: Re: [PATCH 2/2] io_uring: defer alloc_hint update to io_file_bitmap_set()
Date: Fri, 27 May 2022 11:09:44 -0600	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 5/27/22 10:53 AM, Xiaoguang Wang wrote:
> @@ -9650,12 +9646,15 @@ static void io_free_file_tables(struct io_file_table *table)
>  	table->bitmap = NULL;
>  }
>  
> -static inline void io_file_bitmap_set(struct io_file_table *table, int bit)
> +static inline void io_file_bitmap_set(struct io_ring_ctx *ctx, int bit)
>  {
> +	struct io_file_table *table = &ctx->file_table;
> +
>  	WARN_ON_ONCE(test_bit(bit, table->bitmap));
>  	__set_bit(bit, table->bitmap);
> -	if (bit == table->alloc_hint)
> -		table->alloc_hint++;
> +	table->alloc_hint = bit + 1;
> +	if (table->alloc_hint >= ctx->nr_user_files)
> +		table->alloc_hint = 0;
>  }

This branch isn't needed, we'll reset it when failing to get one anyway.
Much better than adding a branch to the fast path.

-- 
Jens Axboe


  reply	other threads:[~2022-05-27 17:09 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-27 16:53 [PATCH 0/2] two bug fixes about direct fd install Xiaoguang Wang
2022-05-27 16:53 ` [PATCH 1/2] io_uring: fix file leaks around io_fixed_fd_install() Xiaoguang Wang
2022-05-27 17:00   ` Jens Axboe
2022-05-27 16:53 ` [PATCH 2/2] io_uring: defer alloc_hint update to io_file_bitmap_set() Xiaoguang Wang
2022-05-27 17:09   ` Jens Axboe [this message]
2022-05-27 17:39     ` [PATCH v2] " Xiaoguang Wang
2022-05-27 18:03       ` Jens Axboe
2022-05-28  1:45         ` Xiaoguang Wang
2022-05-28  1:51         ` [PATCH v3] " Xiaoguang Wang
2022-05-28  2:14           ` Jens Axboe

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