linux-kernel - Re: [PATCH] block: introduce content activity based ioprio

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Date: Tue, 23 Jan 2024 05:06:00 -0800
From: Christoph Hellwig <hch@...radead.org>
To: "zhaoyang.huang" <zhaoyang.huang@...soc.com>
Cc: Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Zhaoyang Huang <huangzhaoyang@...il.com>, steve.kang@...soc.com
Subject: Re: [PATCH] block: introduce content activity based ioprio

On Tue, Jan 23, 2024 at 05:33:52PM +0800, zhaoyang.huang wrote:
>  #define ALLOC_CACHE_MAX		256
> @@ -1069,12 +1070,21 @@ EXPORT_SYMBOL_GPL(bio_add_zone_append_page);
>  void __bio_add_page(struct bio *bio, struct page *page,
>  		unsigned int len, unsigned int off)
>  {
> +	int class, level, hint, activity;
> +
> +	class = IOPRIO_PRIO_CLASS(bio->bi_ioprio);
> +	level = IOPRIO_PRIO_LEVEL(bio->bi_ioprio);
> +	hint = IOPRIO_PRIO_HINT(bio->bi_ioprio);
> +	activity = IOPRIO_PRIO_ACTIVITY(bio->bi_ioprio);
> +
>  	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
>  	WARN_ON_ONCE(bio_full(bio, len));
>  
>  	bvec_set_page(&bio->bi_io_vec[bio->bi_vcnt], page, len, off);
>  	bio->bi_iter.bi_size += len;
>  	bio->bi_vcnt++;
> +	activity += (bio->bi_vcnt <= IOPRIO_NR_ACTIVITY && PageWorkingset(page)) ? 1 : 0;

The block layer must not look at page bits.  I've fixed all this crap
with a lot of work and we're not going to re-add it for another qute
hack.  The place to figure out any kind of I/O priority is the file
system (preferably using generic helpers).