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Sender: Minchan Kim <minchan.kim@gmail.com>
Date:   Fri, 16 Oct 2020 13:29:26 -0700
From:   Minchan Kim <minchan@kernel.org>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>, rajekumar@google.com,
        amosbianchi@google.com, joaodias@google.com
Subject: Re: [PATCH] zram: support a page writeback
Message-ID: <20201016202926.GB1976566@google.com>
References: <20201012071452.1613131-1-minchan@kernel.org>
 <20201016002547.GA2412725@google.com>
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Hi Sergey,

On Fri, Oct 16, 2020 at 09:25:47AM +0900, Sergey Senozhatsky wrote:
> On (20/10/12 00:14), Minchan Kim wrote:
> >  
> >  With the command, zram writeback idle pages from memory to the storage.
> >  
> > +If admin want to write a specific page in zram device to backing device,
> > +they could write the page index into the interface.
> > +
> > +	echo 1251 > /sys/block/zramX/writeback
> > +
> 
> May be we can make it more explicit?
> 
> 	echo "page_index=123" > /sys/block/zramX/writeback
> 
> Just in case of future extensions. E.g. someone might want to
> have something like
> 
> 	echo "idle_nr=123" > /sys/block/zramX/writeback
> 
> which would write_back 123 idle pages max.
> 
> 	-ss

Make sense. I will use echo "block_index" since page size could be
changed later(e.g., some pages are 4K, some are THP).
I will revise it at next spin.

Thanks, Sergey!