linux-kernel - Re: [RFC PATCH] mm: set cache_trim_mode when inactive ratio is undesired

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Message-ID: <YtlglhbLUfGBsvw6@casper.infradead.org>
Date:   Thu, 21 Jul 2022 15:20:06 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     "zhaoyang.huang" <zhaoyang.huang@...soc.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Zhaoyang Huang <huangzhaoyang@...il.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, ke.wang@...soc.com
Subject: Re: [RFC PATCH] mm: set cache_trim_mode when inactive ratio is
 undesired

On Thu, Jul 21, 2022 at 03:06:48PM +0800, zhaoyang.huang wrote:
> @@ -3198,7 +3215,8 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)
>  	 * anonymous pages.
>  	 */
>  	file = lruvec_page_state(target_lruvec, NR_INACTIVE_FILE);
> -	if (file >> sc->priority && !(sc->may_deactivate & DEACTIVATE_FILE))
> +	if (file >> sc->priority && (!(sc->may_deactivate & DEACTIVATE_FILE)
> +		|| inactive_is_high(target_lruvec, LRU_INACTIVE_FILE)))

Indentation is weird here.  When splitting a line, put the operator at
the end, and then indent the rest by something *other* than a single
tab, so it doesn't look like it's part of the following statement.  ie
either:

	if (file >> sc->priority && (!(sc->may_deactivate & DEACTIVATE_FILE) ||
	    inactive_is_high(target_lruvec, LRU_INACTIVE_FILE)))

or:

	if (file >> sc->priority && (!(sc->may_deactivate & DEACTIVATE_FILE) ||
			inactive_is_high(target_lruvec, LRU_INACTIVE_FILE)))

Some people like to use the indentation to illustrate the precendence.
That would look like this:

	if (file >> sc->priority &&
	    (!(sc->may_deactivate & DEACTIVATE_FILE) ||
	     inactive_is_high(target_lruvec, LRU_INACTIVE_FILE)))

(I have a mild preference for the third option in this instance)

>  		sc->cache_trim_mode = 1;
>  	else
>  		sc->cache_trim_mode = 0;
> -- 
> 1.9.1
> 
>