linux-kernel - Re: [PATCHv3 4/8] zram: Introduce recompress sysfs knob

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Message-ID: <Y04LerrIH9KTJM2A@google.com>
Date:   Tue, 18 Oct 2022 11:12:10 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Minchan Kim <minchan@...nel.org>,
        Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCHv3 4/8] zram: Introduce recompress sysfs knob

On (22/10/17 17:08), Andrew Morton wrote:
> > Allow zram to recompress (using secondary compression streams)
> > pages. We support three modes:
> > 
> > 1) IDLE pages recompression is activated by `idle` mode
> > 
> > 	echo idle > /sys/block/zram0/recompress
> > 
> > 2) Since there may be many idle pages user-space may pass a size
> > watermark value and we will recompress IDLE pages only of equal
> > or greater size:
> > 
> > 	echo 888 > /sys/block/zram0/recompress
> 
> It's helpful to describe the units ("bytes") here and in the
> docmentation.

Will send fixup patches.

> > 3) HUGE pages recompression is activated by `huge` mode
> > 
> > 	echo huge > /sys/block/zram0/recompress
> > 
> > 4) HUGE_IDLE pages recompression is activated by `huge_idle` mode
> > 
> > 	echo huge_idle > /sys/block/zram0/recompress
> > 
> > ...
> >
> > +	if (IS_ERR((void *)handle_next)) {
> 
> IS_ERR_VALUE() avoids castsing back and forth.

Thanks, I'll send a separate patch for this (if you don't mind).