linux-kernel - Re: [PATCH v5] zram: Introduce an aged idle interface

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Message-ID: <YVJ8mSOwdWzyqIMz@google.com>
Date:   Tue, 28 Sep 2021 11:23:21 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Brian Geffon <bgeffon@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Minchan Kim <minchan@...nel.org>,
        Nitin Gupta <ngupta@...are.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Jonathan Corbet <corbet@....net>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-block@...r.kernel.org,
        Suleiman Souhlal <suleiman@...gle.com>,
        Jesse Barnes <jsbarnes@...gle.com>
Subject: Re: [PATCH v5] zram: Introduce an aged idle interface

On (21/09/24 09:11), Brian Geffon wrote:
[..]

Some silly nits:

> +static void mark_idle(struct zram *zram, ktime_t cutoff)
>  {
> -	struct zram *zram = dev_to_zram(dev);
> +	int is_idle = 1;
>  	unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
>  	int index;
>  
> -	if (!sysfs_streq(buf, "all"))
> -		return -EINVAL;
> -
> -	down_read(&zram->init_lock);
> -	if (!init_done(zram)) {
> -		up_read(&zram->init_lock);
> -		return -EINVAL;
> -	}
> -
>  	for (index = 0; index < nr_pages; index++) {
>  		/*
>  		 * Do not mark ZRAM_UNDER_WB slot as ZRAM_IDLE to close race.
> @@ -314,14 +308,49 @@ static ssize_t idle_store(struct device *dev,
>  		 */
>  		zram_slot_lock(zram, index);
>  		if (zram_allocated(zram, index) &&
> -				!zram_test_flag(zram, index, ZRAM_UNDER_WB))
> -			zram_set_flag(zram, index, ZRAM_IDLE);
> +				!zram_test_flag(zram, index, ZRAM_UNDER_WB)) {
> +#ifdef CONFIG_ZRAM_MEMORY_TRACKING
> +				is_idle = (!cutoff || ktime_after(cutoff, zram->table[index].ac_time));

checkpatch "WARNING: suspect code indent for conditional statements (16, 32)"

Looks like `is_idle` is at one extra indent level.

> +#endif
> +			if (is_idle)
> +				zram_set_flag(zram, index, ZRAM_IDLE);
> +		}
>  		zram_slot_unlock(zram, index);
>  	}
> +}
>  
> -	up_read(&zram->init_lock);
> +static ssize_t idle_store(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t len)
> +{
> +	struct zram *zram = dev_to_zram(dev);
> +	ktime_t cutoff_time = 0;
> +	ssize_t rv = -EINVAL;
>  
> -	return len;
> +	if (!sysfs_streq(buf, "all")) {
> +		/*
> +		 * If it did not parse as 'all' try to treat it as an integer when
> +		 * we have memory tracking enabled.
> +		 */
> +		u64 age_sec;

checkpatch "WARNING: Missing a blank line after declarations"

> +		if (IS_ENABLED(CONFIG_ZRAM_MEMORY_TRACKING) && !kstrtoull(buf, 0, &age_sec))
> +			cutoff_time = ktime_sub(ktime_get_boottime(),
> +					ns_to_ktime(age_sec * NSEC_PER_SEC));
> +		else
> +			goto out;
> +	}
> +
> +	down_read(&zram->init_lock);
> +	if (!init_done(zram))
> +		goto out_unlock;
> +
> +	/* A age_sec of 0 marks everything as idle, this is the "all" behavior */

	s/age_sec/cutoff_time/

> +	mark_idle(zram, cutoff_time);
> +	rv = len;