linux-kernel - Re: + zram-support-compaction.patch added to -mm tree

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Date:	Thu, 5 Mar 2015 14:29:42 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	minchan@...nel.org
Cc:	akpm@...ux-foundation.org, ddstreet@...e.org, gunho.lee@....com,
	iamjoonsoo.kim@....com, jmarchan@...hat.com, juno.choi@....com,
	mel@....ul.ie, ngupta@...are.org, semenzato@...gle.com,
	sergey.senozhatsky@...il.com, sjennings@...iantweb.net,
	mm-commits@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: + zram-support-compaction.patch added to -mm tree

On (03/04/15 14:02), akpm@...ux-foundation.org wrote:
> +What:		/sys/block/zram<id>/compact
> +Date:		August 2015
> +Contact:	Minchan Kim <minchan@...nel.org>
> +Description:
> +		The compact file is write-only and trigger compaction for
> +		allocator zrm uses. The allocator moves some objects so that
> +		it could free fragment space.
> +
> +What:		/sys/block/zram<id>/num_migrated
> +Date:		August 2015
> +Contact:	Minchan Kim <minchan@...nel.org>
> +Description:
> +		The compact file is read-only and shows how many object
> +		migrated by compaction.
> diff -puN drivers/block/zram/zram_drv.c~zram-support-compaction drivers/block/zram/zram_drv.c
> --- a/drivers/block/zram/zram_drv.c~zram-support-compaction
> +++ a/drivers/block/zram/zram_drv.c
> @@ -70,6 +70,27 @@ static inline struct zram *dev_to_zram(s
>  	return (struct zram *)dev_to_disk(dev)->private_data;
>  }

First of all, my apologies to Andrew Morton. if I reply to this email, my mutt for
some reason replaces akpm at linux-foundation.org with linux-kernel at vger.kernel.org
(I can't see why this is happening, but this is somehow a `stable behaviour'). I didn't
spot this, so this is why Andrew was not Cc-d to my previous reply to this eamil.




rather a discussion question.

Minchan, do you want to provide num_migrated as part of zsmalloc stats rather
than having yet another zram attr? we already provide zsmalloc stats and this
type of information seems to belong there. just idea.

	-ss

>  
> +static ssize_t compact_store(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t len)
> +{
> +	unsigned long nr_migrated;
> +	struct zram *zram = dev_to_zram(dev);
> +	struct zram_meta *meta;
> +
> +	down_read(&zram->init_lock);
> +	if (!init_done(zram)) {
> +		up_read(&zram->init_lock);
> +		return -EINVAL;
> +	}
> +
> +	meta = zram->meta;
> +	nr_migrated = zs_compact(meta->mem_pool);
> +	atomic64_add(nr_migrated, &zram->stats.num_migrated);
> +	up_read(&zram->init_lock);
> +
> +	return len;
> +}
--
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